I'll be bold here and say that many of the responses you've recieve are not totally accurate AND also say that you need to see a good ophtomologist before moving forward. Though Dr. Steinspar is being a little colorful in his comments, he is correct. You may have mild ptosis, worse on the left than the right. ALSO, you may have an anatomical difference between the two eyes in that the left may be slightly lower that the right due to a larger orbit or lower orbital floor.
In any case simply removing some skin will confuse your surgeons and ultimately make you very upset with the outcome. Your issues are correctable but you want to see an experienced eyelid and orbit surgeon who can address the whole issue.
I'll attach a bit of info.
Chase Lay, MD