Cycles can be different length and totally normal. I have no idea what you mena by 30-28 day cycles. Do you mean is it normal to have a cycle that is 28 days or 30 days in length? Yes, it is. Or are you asking if you risked pregnancy? You do risk pregnancy any time you have unprotected sex. Let's hope it was after you ovulated but you won't know until your period does or doesn't show.