Welcome to 3fat chicks, cutiecookie,
There could be several reasons why you haven't lost weight. First of all, you say you are on a low-fat diet. But do you keep track of your calories too? A lot of low fat foods are loaded in sugar. Also, have you had your thyroid checked? Maybe you have a physical reason that your doctor hasn't found. Also, maybe the combinations of medicine are interacting with each other. And don't forget that muscle weighs more than fat, so maybe all the exercising has affected you that way.
If none of this applies, have a heart-to-heart with your doctor. Good luck to you!
85 pounds lost with Vertical Sleeve Gastrectomy
110 pounds lost from highest weight