Due date confusion

Katy
Hi everyone ! I've just got my BFP! I'm abit confused with how many weeks I am. I had a 32 day cycle then I started taking pregnacare conception and it messed up my cycle! My last cycle was 39 days. The first day of my last period was 25 April and I got a positive opk on 12th May so quite confused with how many weeks I am. 
Could someone help me calculate it pleaseeeeeeeeeee