I've never been a proponent for any kind of diet pills, particularly, the ones like phentermine that can cause issues with heart rates, anxiety, etc.
I'm in the same boat you are and I'm trying very hard to lose the weight I gained when my thyroid wigged out on me; I'm also "borderline" type II diabetes. Do make sure your thyroid hormones are at a point that's good for YOU, not just "in range".