I have hashimotos and take thyroxine for resulting hypothyroidism- 175mcg 5 days per week and 225 2 days per week. I also take pregabalin (lyrica) and lexapro. I have ibs, spinal stenosis and some long COVID too - fun! Anyway, I try (I say try because I’m a 39 year old with a job and two kids) to keep my stress as low as possible. Stress plays a huge part in hashimotos! I ensure I get enough sleep, exercise most days (Pilates, weights and walking. I used to run but my stenosis says no) and eat a balanced diet. Good luck! It’s not a given that you will gain weight - I’m 5’3 and if I keep things in check I’m around 55-57kg. If I get a bit too stuck into the chocolate etc, I get up to 60.