My left cheek looks bigger than my right cheek. i had my lower right 1st molar tooth removed many years back since then mostly chew with my left side

Collapse: You may have bite collapse on the right side where the tooth was removed and never replaced. This can make your right cheek look sunken in. Please see an dentist to have your occlusion evaluated.

See a dentist: I would have this checked, just to be preventative. Balance is important in chewing and facial symmetry.

Unbalanced chewing: Since you are doing most of your chewing on the left side the muscles on that side of your face are working harder. The more you work a muscle the more you build it, since your bite is not balanced the left side muscles are working harder so have been built up.

If you're asking why: the right cheek appears smaller, it is because the cheek sags into the space left by the missing tooth. Also as you usually chew on the left, you may have built up the left cheek muscle by giving it more exercise That will make the left cheek more prominent.