Trying to figure out how far along I am ?

Hannah

So I was on birth control and it stopped my period so I started to take opk when I stopped just to see if my body was getting back to normal and on 5/6 I got a positive opk peak and on 5/7 I did have sex and I tested on the 20th and my test was positive so not having a period to go off of to see how far along I am I’m going off of the opk peak date so do u think I would be about 4 to 5 weeks along ?