I hope things get better for you. I think the ladies here have given awesome advice.
I just wanted to come in and say that for me (my hair is also fine and multi-textured) henna acts like a protein. If I teamed henna with any other protein product, my hair was NOT happy at all. And at most, I did henna once every 1-2 months. It wasn't something I could use bi-weekly without issues.
I later learned that henna glosses worked better for me. (henna with conditioner). ACV is evil for my hair. It literally starts to break ALOT.... so while it works for alot of naturals, I have to leave it alone.
Definitely get your levels checked. I have PCOS and it definitely affects my hair. I had dangerously low vitamin D levels and had to take 50,000 I.U. once a week for several months. I was also borderline anemic. Find out what's going on with your system, then react accordingly. Definitely do your research on the results given to you. I prefer going more holistic routes but that's not always feasible for every situation.
As for your twa, maybe you're doing a bit much? During this time, you play with loads of products to see what your hair likes best, but if it's not working for you... don't keep using it. My grass hates aphoghee (everyone else raves about it), AOHSR (over perfumed gar-baaj lol), and KCCC ( girl just.... nooooooo lol) so I realized that after several trial and error situations, I had to use what works for me and my hair. It could be a matter of finding the right products. Maybe you should moisturize, seal, then twist it up and/or put it away. I wouldn't try weave or extensions on delicate tresses, but maybe a nice wig would work for you?