I've been on birth control since I started my period at 17, I've never had normal periods until last year I'm now 23, I've never tracked my periods either since I'm now trying to conceive my rainbow baby. Is every females period off monthly. The last 6 month my periods come say the 10th then the next month it will be the 17th and it goes back and forth like that some months it will be every 3 weeks then some months every 5 weeks is that normal?