Help? (Tmi warning)

Ok warning there might be some tmi in this post. Be warned.

I'm not on birth control. My mom said she doesn't want me to be because she's worried I'll have lots of sex. My periods have normally been regular for the most part. Lately my periods have been getting to be 2-3 weeks apart which is not normal for me as mine are normally 4 weeks apart.

So I've been getting really sick lately and Everytime I go to the Dr they still can't figure out what it is. All They said was I have low thyroid levels which could affect my hormones.

So now it's been 19 days since my last period and I just got it again today. I also got sick again on Saturday which is exactly the same day I got sick like two weeks ago. All the symptoms are the same, and even the days match up.

I'm beginning to think this has something to do with my hormones rather than just being sick. Do you guys think birth control would help at this point or make it worse?

Please help. Anything you think of please lmk. Literally anything can help.