I'm sure you'll find all the support you need here. I'm also hyperthyroid but i don't find it has anything to do with my weight gain and loss since i take meds. I've been taking them for years.
The other day i read with some astonishment that this disease really only causes weight gain to a comparatively small amount. I wish i had kept the link.
If your parents/family are being overly critical, perhaps you could calmly explain to them that their critical feedback doesn't actually help but makes it harder. Tell them you need them to keep quiet with the criticism and judgementalism.
If its because they are eating a lot of bad foods in front of you, well that's probably harder to deal with. I find i need to avoid the sight and smells of the foods that i have difficulties with.
If they are offering it to you, keep telling them that you want them not to offer you food until they get it.
Best wishes on your journey.