Dr Mew wrote the following in the comments section on his video about intermolar width:

"Important note; modern adults (or anyone over the age of 9) tend to have a molar width of 29 to 34mm. Anyone with 35 to 38mm will find it much easier but still very hard to make progressive improvements without any formal therapy, and as a rule of thumb when I finish therapy any one who can maintain 38mm or more without retainers tends to maintain good alignment almost indefinitely, with a minimal effort."

So with your intermolar width of 38mm, Dr. Mew says that progress is challenging but possible without "formal therapy." I take this to mean that you should have adequate tongue space to achieve improvement through oral posture alone without the need for an expander appliance. If you are struggling to fit your tongue on the roof of your mouth, maybe an expander would still be helpful. One thing that has occurred to me is that if one side of my arch is relatively straight like a V while the other side is more curved like a U, the acrylic of the expander will maintain that alignment as it separates whereas the tongue will automatically adapt to any asymmetries. My intermolar width is 34mm, so I plan to use an expander to get more tongue space, and use my tongue to finish and then maintain the improvements to my facial form.

They say when you have enough space for the tongue. But honestly might as well use it since it seems to be quicker. Or alternate between using it and your tongue

Yeah, I have the U shaped left side, and V shaped right. With this, do I just maintain symmetrical pressure and eventually it will even itself out?

The main asymmetry I see is just some crowding making your right canine a little forward and/or the right lateral incisor a little back. Is your dental midline shifted to the right, or is that just the angle of the impression in the tray? If you have already ordered the expander, I would go ahead and use it. Once you have gotten as much expansion out of it as you can, and maybe a few months using it to cement as much of the separation as you can, then move on to focusing on tongue posture alone to fine tune the alignment, which should correct itself without the crowding of a narrow arch. If not, ultimately you could use clear aligners to close gaps, etc. In another thread, TGW wrote about making modifications to the acrylic of the expander as you progress with treatment. If you find as you are expanding that the acrylic is holding that right canine in its forward position you might be able to file down some of the acrylic behind it to allow it to line up with the buccal side of the surrounding teeth.

Yes, my midline is shifted right. When I smile, the center of my incisors is slightly to the right of  my nose.

that's an interesting idea to shave off some to allow more expansion on the other teeth to allow the canine, and lateral incisor to align themselves.

For a long time I was mostly pushing hard on my right side, as that's the side with tmj and the crowding, but lately I have been experiencing a popping on the left side as well, but in a different fashion than the tmj side experienced. I'm not sure if that could have increased the shift to the right side.

I'm jealous that you still have your third molars! You'll need wider arches to fit all of your teeth without crowding than I will without my wisdom teeth.

Haha, when asking my dentist to get braces, (as is required for my insurance, to be referred by the dentist) he told me that I'd most likely need 4 premolars extracted. I wouldn't have let that happen having known about Orthotropics for the past 2 years but effectively using the information for the past year, somehow stumbling across the correct swallow, where has a woman demonstrating how to swallow, after finding out about vitamin k2. Finding out this information early is really great, and I really encourage the knowledge to be spread.

Also with everything about success with adult patients, and the FAGGA appliance, there's so much that's incredible about Orthotropics, and it's quite literally changing lives.

I can't wait for my lower wisdom teeth to grow in and have the back molars chewing together.

[In media res  A question to this group: I was thinking that as a framework for expecations, if one were to measure the width of their tongue then they would know the amount of minimum expansion necessary/minimum potential expansion to strive for.  Anyone here....measure their tongue width or have a protocol for that? Hypothetically, stick your tongue out and measure at widest point? Or what?]

So it is established that, at the minimum, one should strive for expanders until the tongue can optimally rest against the palate.  That is one of the foundational benefits of expanders, and seen as the basis for recommending expanders.
That appropriate width is determined by your tongue's width.

In Mew's video on Semi-Rapid Expansion he talks about cases of "10, 12, and one particular case, 24 mm of expansion" using semi-rapid expansion! He doesn't address the age so let us err on the side of caution and say it is a child that achieved 24mm of expansion.  So semi-rapid expansion is quite useful, but of course risky in those that are being vigilantes in the process. 

I say... keep using the expander until the width of the palate is equivalent to the width of the tongue.  The high arches in smaller mouths are supposed to flatten over time.  I say expand until the tongue can rest flat against the [newly 'flattened'] palate. 
Nevertheless, teeth tipping is seen as a problematic byproduct of expansion, so also use the increase in teeth tipping as a sign to stop perhaps.

Also, it is quoted that 42 mm Schwartz width is the preference of modest dentists.. so that too is a minimum.  That is likely established by a bellcurve and is not representative of maximum potential as reinforced by Apollo's post. If you have a tongue that is much wider than your mouth then you would potentially go for more.

That is how I am framing this for myself, for now.

Posted by: Gregory

[In media res  A question to this group: I was thinking that as a framework for expecations, if one were to measure the width of their tongue then they would know the amount of minimum expansion necessary/minimum potential expansion to strive for.  Anyone here....measure their tongue width or have a protocol for that? Hypothetically, stick your tongue out and measure at widest point? Or what?]

I think it's right that the amount of expansion you need depends on the size of your tongue, but I'm not sure that measuring the width of the tongue corresponds to our goal intermolar width. When I open my mouth and flatten my tongue out over the biting surface of my upper teeth, it seems to naturally reach to about the width of the outer buccal cusps, but with effort I can expand it even farther. If my molars are about 10mm in width, that would mean 20mm of palate expansion to reach the width that my tongue seems to rest naturally. This is well beyond the maximum separation of the expander screw. For me that would result in a final intermolar width of approximately 34mm + 20mm = 54mm. This might be close to my genetic potential, but it probably isn't a very realistic goal, and my tongue is able to flatten out even wider to more than 60mm. I plan to see how much separation I am able to achieve with the expander, and then monitor if my intermolar width regresses back down or continues to expand when I phase out the appliance and rely on tongue posture alone.

Fair enough. I see where you are coming from. 
I just wanted something tangible to strive for beyond "let's do our best," know what I mean?