I started taking Yaz about a year ago. Six months afterward, my previously normal TSH level hit 12! (that's really high--no wonder I felt terrible). Nothing else had changed. My regular doctor looked it up and saw that studies have shown that on average, starting birth control pills can make the body need 25 mcg more thyroid medication per day. This isn't an issue if you have a functioning thyroid, since it will just increase it's production.
Apparently, despite how common these medications are, a lot of doctors don't seem to be aware of this issue. I would have thought that my gynecologist would have known--apparently not. The insert that comes with either medication says nothing about this. This is rather unacceptable.
I do find it odd, though, that we all seem to be taken Yaz....maybe that medication has more of an issue than others with this?
Anyway, ask your doctor to increase your dose by 25 mcg and you should feel better in a couple of months, at the most.