Unwanted Weight Gain from Medications

Hi! I have hypothiroidsm and anxiety. I take levotitoxine and sertraline. My thyroid hormone levels are now ok but I have been struggling to loose weight. Every nutricionist and doctor tell me to eat less and exercise more; which I do; also have tried every diet you can think about. Nothing has worked :( I loose very few pounds in one month of diet and if I cheat on my meals once.. I gain what I’ve lost. It’s so frustrating. They think I lie about what I eat or exercise because they tell me that sertraline has nothing to do with gaining weight but I have read some articles that claim that it actually contributes to that. Next month I have a blood test to check my T3; the doctor says that depending on the level he might prescribe NP thyroid which includes t4 and t3 hormones. He says it can help to boost my metabolism and loose weight. Not so sure as I have read that T3 can elevate anxiety symptoms 😥 so I am a bit worried.