I think you are going about it the right way.
Be honest with your doctor and I would start your new habits now before you see the doctor. My primary physician is not allowed to prescribe Phen (this is because the Military does not allow them to which really makes me mad) but she does believe that if you use it the right way, i.e. as a tool not a crutch, that it can be very helpful. She actually quietly told me about a local Women's Clinic (OBGYN type office) that does do the
program with the supervision of one of the doctors and they do give the Phen, but there are certain things they require, you have to be a certain amount of weight over your standard weight (not sure what that is because it is different with everyone via age, bone structure height and weight) and a minimum of 3 pounds a month must be lost to get the next months prescription.