I can relate to your anxiety ..I'm going thru the same thing. My date is Oct 16 ..8 days away. I have been jumping thru hoops for a year now and was ok'd just yesterday. I have also had depression after previous surgery. I worried I'll not lose, scared I'm gonna lose my hair, etc. etc. Same as you I have always been big..I don't know how to be thin.
I read all the posts and go to a support group and know my life will change and I have faith in my surgeon and the people here that I can do it..and so can you. I don't know how old you are but your fortunate to have the surgery before any health problems arise. Good luck..we are both doing the right thing.