The GOAL of Synthroid is not weight loss. Any doctor that tells you that Synthroid will cause weight loss is greatly overstating the ability of T4.
Correctly balancing your thyroid will help you lose weight. Until the thyroid and other hormones are in balance, weight loss will be very difficult. Since you are under a doctor's care, and have been for quite awhile, I think the best thing is to discuss possible pils and such with him/her. If you are not happy with the results or care he/she has given you - change doctors.