Could be that your tongue is out of position, but it could also be either of your jaws. 

If the maxilla is underdeveloped on one side, or if the mandible is off-center to one side

I have been mewing for the past five or six months and have a similar issue. My palate is uneven, and my tongue tends to hit the right side of my palate and teeth more than the left. It has been a constant struggle, but it has improved a great deal.

One of the things I have realized lately is how important head posture is when it comes to asymmetries.  You want to make sure that your head is balanced and not tilting in one direction or the other. I tend to tilt my head to the right so I started doing neck yoga, which is just a series of stretches for the neck. In addition, lately I have been practicing an exercise, where I tilt and turn my head in various directions, and swallow my saliva in each of those directions. This works out various muscles in the tongue and swallow structure, strengthening areas of weakness and providing balance. In the short time I have been doing this, the unevenness of my palate has improved greatly.

My advice… Focus on your swallow. Practice the cheesy smile swallow and the very very cheesy smile swallow. And create a balance in your head, neck, and body posture, as well as a balance in the musculature of your swallow.

https://youtu.be/gcI8CvoFxfQ

https://youtu.be/lKaW3zNIuWY

Hope that helps.

Hi, although I’m quite new to mewing I think i can be to help. I experience the same thing. Try feel your palate with the help of your finger. Even though my left side has a better cheekbone, the left side of my palate is still more narrow and when I mew I feel my left side getting worked more. My educated guess is That the imbalance Will correct itself from mewing as you would normally and the the palate will get more symmetrical until you can mew correctly. Hope this helped😄

I noticed the same as last answerer, completely natural, u don't have to reach the other side of front palate.

If you sleep on your stomach and it's comfortable on one side but feels like you are breaking your neck on the other, sleep on the uncomfortable position(to push chin up and stretch those muscles).

If you hold your head with the same arm, do it with the other(where the chin is deeper). But the best is if you keep doing correct head posture, lots of chin tuck. Unless you are watching something on a projector on your sides which is annoying.

Hold your phone in the other hand, type with both hands.

If you tilt your head, your eyes are upper on the hollow side, the deeper side, you do this especially while reading, but not the end of the world.

Your teeth might be deeper on the hollow side(from the two front ones, you can see the most difference)

If you have scoliosis don't hold bag on same side, skretch down on your upper shoulder,  skretch toward your upper shoulder. And if your hips are upper too (S spine) on the same side as your shoulder, hold your legs toward the side where your shoulder or shoulderblade is lower, this way your skin is pushing your hip bones down(you can do this when sleeping or lying watching film at home). And don't cross your legs with the upper hip leg on the front. (When you sit with crossed legs and you can't touch the ground only with one of your knees, it's not because it's inflexible but bcs the hip is higher). Your rib might be hollow on the same side as where your face is hollow. 

I didn't know I have scoliosis cuz my shoulders are usually on the same level but that doesn't mean I don't have some of it. 

^@liamcg are you sure btw? :D

Her higher shoulder is not noticable either. https://www.ellefitactive.com/blogs/testimonials/interview-how-stretching-and-strength-training-has-helped-my-scoliosis

Buy a backpack if you have shoulder bag