20 year old with diffuse thinning, how bad is this?

[Whatneedsapoint]

Hello, new here. Sorry for my english because it is not my first language.
For the past 2+ years my hair has been thinning. I do not know why- the thinning hairs is all over my head (back and sides included) and all over my body. It takes longer to grow it out now, and when it does it is thinner with less volume.
My hairline hasn't receeded much yet, and there isn't really any baldness in my family.
I think it may have to do with underactive thyroid- because my mother and her father both have it but have yet to have it adressed. I've been using minoxidil/caffeine shampoo for a little bit now but am feeling like garbage because of it.
please look at this imgur album:
https://imgur.com/a/Tr5V7
how bad is it?