First of all well done for getting this far, you have a long road ahead but there is plenty you can do to get back your health. I've been hypo all my life and here is my advice:
Read the Stop the thyroid madness blog, it literally saved my life.
Do your upmost to move to natural thyroid meds like armour, naturethroud they give you all the hormones unlike synthetics. See if your gp will do this otherwise you will have to go privately
Go gluten free, cut down on dairy and sugar.
Get tested for Hashimotos
Get adrenal testing as this is the cause of a large part of weight gain
Don't over exercise as this will raise cortisol levels and lead to belly fat
Try to get a full panel of testing for iron, vit d, b12, adrenals, thyroid.
Join NDT supportive Facebook groups for support and help interpreting your blood work.
This is just the start. I won't lie it's going to be intensive and expensive as you will have to be your own health advocate and pay for testing and supplements. Read everything you can about it and ask questions. But there is light at the end of the tunnel so don't give up. There is no cure so better to arm yourself with knowledge now so you can have good health.