Sex 2 weeks after sons birth...

Sooo my son was born on 7/7/18 and this was an extremely easy birth compared to my daughter 2 years again. i pushed him out in 3 contractions and had no tearing, stitches etc. i was up walking right after and had no complications whatsoever. i stopped bleeding a week after i had him and wanted sex so bad. sorry tmi. i understand you are supposed to wait 6 weeks due to infection risk, recovery etc. well today was my sons original due date. he was born at 38+1. and my boyfriend came in me. well ive been exclusively breast feeding and they say it is a form of birth control. so my question is are my chances really high or slim for getting pregnant? and how long should i wait to take a test?