Diet/sport vs.hypothyroidism and antipsychotics

Hi,
I’m 35 and I do want to ask do you have some experience/ideas about what could I do.
I’m not a beginner and I have never previously experienced problems with controlling my weight and I never experienced any troubles, despite regularly taking medicines which usually cause weight gain.
But for more than a year I’ve experienced complete stagnation – since my thyroid started to malfunction and obviously I’ve developed some kind of metabolic complex. I have no idea what to do
I’m very active between March and October – 50 up to 90 km a day . I’m also doing 2 strength trainings – rather short, but intense.
I do try to eat at least BMR + what I get from bicycle computer -10% – yet I can’t loose a single kilogram for months. The problem is that if I go under certain level of energy intake I’m waking up at night and devouring random foods.
Most of dietician where I live, ditch me the moment I mention mood stabilisers and antipsychotics. Hypothyroidism on the top of that appears to by final reason to avoid me.
Could anyone at least suggest how to approach subject of calories intake in this situation? I know it seems a bit complicated but I don’t look for the solution, I look for advice and opinion

Diet/sport vs.hypothyroidism and antipsychotics