Change of pill

Abbi

Hey guys.. I changed my pills to a progesterone only pill as I had an ocular migraine and it was dangerous to be on a combined pill. I've been taking it for 21 days (it's a 28 day pill cycle) and I got my period. I was wondering if any other people out there got it so quickly after taking not even the whole 28 days. ☺️ thanks!!