my advice about the masisve weight gain stuff (i feel your pain!) i would go to holland and barrett for an allergy test, to get one on the NHS the wait time is about 6 months IF you can get a GP to refer you at all.
one thing i would say is dont rule out lactose intolerance, ceoliac disease (the most undiagnosed illness in the uk) and a wheat allergy.
I would also suggest that you take a pro biotic even now, try to get that gut healthy
above all, keep it up, the fat cells you have will eventually learn they dont need to be refilled and stop trying to be.
it takes time for your body to reach equilibrium with its new size x