Why are my eyes a different shape and size? (photo)

The condition affects the two sides differently and there is different amounts of compensatory brow elevation. This issue would not be very visible to others.  So If you find yourself spending many hours a day being concerned about this or are avoiding social situations, you might also be suffering from a condition called body dysmorphic disorder.  It that is the case, a psychologist can be helpful in gaining insight into these feelings.  If you do ultimately have eyelid surgery, less is more.  Proceed with caution.

It appears that you have a very mild asymmetry with one lid slightly higher/lower than the other. From the photo, the height difference appears very small, probably too small to necessitate a surgery.If you are concerned, make sure you are evaluated in-person by an experienced oculo-facial plastic surgeon who can do a formal examination of your lids and make appropriate recommendations.

It appears that you have eyelid ptosis. There are multiple reasons that this can occur and should be evaluated by an oculoplastic surgeon. Best wishes.