Confused!!!! Need advice!

I just got a positive opk CD 17!!! But!! I'm on CD 17 because i got my af on the 18th instead of the 21st! So 4 days early. So I'm just hoping its not too late. But if my af is going back to normal I should be ovulating on CD 14. Make sense? Like if my af wasn't 4 days early if be on CD 13 today instead of 17. I need advice! It was also a very heavy period and lasted 5 days. That NEVER happens to me, like ever.