Your right eye looks bigger because you have a very slight droop (ptosis) of your left eye. The question is why have you developed a ptosis in the last two years? There are some medical conditions that can give rise to this problem and they should be ruled out first. If you have already seen an ophthalmologist, they should have discussed this with you and done some investigations. If medical conditions have been ruled out and you have a ptosis with no underlying pathology, then a surgical correction is possible. However, as your ptosis is so slight, overcorrection is a possibility.
You appear to have very mild ptosis of the L upper lid. This can happen as we age and the typical diagnosis is levator dehiscence or laxity. It is treated in many ways but a plication can correct it. The difficulty in your case is that the degree of ptosis is very mild and overcorrecting it can be an issue. Consult with a board certified plastic surgeon who can educate you on the procedure.