Wow, glad you posted. I'm dealing with the same thing and not many people have addressed it here. 

Personally, I'm not sure if mewing alone can fix this. I believe the issue is that your maxilla is actually also asymmetrical, and that you lower jaw moves to that side to compensate and maintain occlusion. Therefore, one needs to expand the upper palate *moreso in one direction than the other*. This is something that could be done with mewing alone, but it might be better to work with an ortho that could use some appliance to expand the palate more in a given direction

Do you chew evenly on both sides? Chewing stimulates bone growth (maxillary and mandibulary) and it also strengthens the masseters. If you have a tendency to chew more on one side, that would affect the jaw's symmetry. 

I didn't know how to post multiple images, but here's the bottom part.

To answer your question, yeah. I typically chew on the bigger side, and when I sleep I lay on it too (with hopes that during night time it'll shift over and even out)

Hey there, I also have an asymmetrical jaw, due to uneven chewing, and bad posture combined with scoliosis that twisted me up over the years. My left side is more recessed than my right, and my ramus on my left side is either shorter or appears shorter, so my lip line looks severely diagonal.

You do not have to upload more, but it's a little difficult for me to see your exact asymmetries with the close up photos, but it appears that your lip line is pretty even. If so, it makes me think that you're dealing with the recession on one side, but not huge differences in ramus length.

@ayla31 is right in my opinion. Your uneven chewing stimulated growth on one side more than the other. I would suggest evening out your chewing. There's a bit of debate on whether or not to focus on your recessed side even more to counteract, or to practice balance from the get go. 

You might also want to take a look at your posture, and see if there are adjustments you can make to impact balance on each side even more.

Other people might have better suggestions! But since practicing oral posture, and working on my chewing, swallowing, and body posture, I have noticed an evening out of my lip line, and my left ramus seems to be popping out a bit more.

Hey Op i had a similar issue where one side of my jaw was sunken in like that. Chewing tough gum on both sides has helped make my weak side stronger overtime. 

I agree with @Sclera as well, body alignment is also important, since tension in muscles can distort bone's position. So your jaw may also be jutted to one side, but that's difficult to see with only fotos (you would have to use your body awareness to determine that).

If thats also the case (in addition to the other stuff), I would rather chew evenly instead of trying to chew more on the weak side, since you dont know if your mandibles joints are in the right position. They could be slightly "dislocated/misplaced" through tension and poor use. And chewing like that could wear the joint down easier since it doesnt sit/rest properly on the socket.

But that can be remedied if the jaw muscles are relaxed, your body is aligned and with bone/facial growth to have enough space. 

Again, I dont know what exactly is going on there, but I would be cautious with over chewing (in case you find it tempting).

Also, the myofunctional therapist Joy Moeller recommends sleeping on your back. Many people find it easier to maintain the mouth closed in this position, too.

I had similar asymmetry..my right side was fully developed than left..chewing have helped me a lot..my face still has asymmetry but not like before..