Still Gaining Weight Back!

This is so frustrating!  I'm gaining back the weight I lost and I'm not doing anything to justify the weight gain.  Most of my 30's were spent pretty much unhappy with my weight and how I look and now that I am 39, if I don't get something fixed soon (my thyroid), I'll spend my 40's unhappy and unhealthy as well.  Vitamin and mineral supplements might help rev up my thyroid.  Perhaps phentermine would rev up my weight loss! I don't want to be this big anymore.