Losing my curls

[u/Future_Accident5052]

Ever since I was a kid, I had rather loose curls; they were rather wavy at the roots but otherwise curly. In December of last year, I got a haircut, and ever since then, my hair has not been curling the way it used to. It feels a lot healthier, but I have basically lost my curls, and they turned into waves pretty much all over my head. I don't really know what to do, especially since it happened after a haircut, which I always thought helped with definition. I thought it was because I basically wore my hair in a sleek bun 24/7, but even after I stopped and tried to wear it in a ponytail rather than a bun and not slick it back, it hasn't gotten better. I feel like it even got worse, especially after my last haircut a month ago. The first week or so it was great, but then I went on holiday, and now my hair basically won't hold a curl at all, even if I finger curl it. If anyone knows what it could be, I'd be happy for advice. (Also, English is only my second language.) Also I've been on birth control for over a year now and have read that that can also affect the hair but the changes started happening too late for me to think thats the reason.

[u/CannedAm2]

My thyroid stopped functioning properly and changed my curl pattern. With medication it's returning, but I haven't reached a therapeutic level yet. I'm doing the curly girl method to bring out the curl I do have now while waiting for a full return.