In fact the look of your eyes changed not because of your eyeglasses, but your myopia. The shape of your eyeballs is changed when you become nearsighted. When you get myopia, your eyeballs are changed from spherical to oval. As a result, your eyes look smaller than before. As your prescription gets heavier, the change becomes more noticeable.
If you have long time worn the eyeglasses, you will have the symptom of reshaping your eyes which will make the eyes look smaller than before. Usually the reflection principle will also make your eyes look smaller through the thick eyeglasses lenses. You need to take off the eyeglasses and change to have the good rest for a while. It will be healthy and helpful for your eyes health.
That's totally normal, the lens is like a magnifying glass so that when you look through you can see what you are looking at bigger and clearer, so in return it is going to make your eyes look bigger when someone is looking at you with your glasses on. its not like making ur eyes a different size they are just magnified. getting contacts will help, because the magnifier there is only in a certain spot and it wont magnify your eyes at all .
Glasses are bent like Magnifying glasses so they "magnify" your eyes. Contacts would not help but try putting a little white eye shadow in the inner corner of your eyes. This makes your eyes look bigger and more awake.