TTC need advice

Hey guys I’m 20 I have a 3yr son and I’m TTC I was on the implanon birth control for 3 years after having my son. I got off this year in August on the 21 I had a period Sept 22-Sept 27th after that I’ve been 41days late and I’ve taken test after test for them all to say negative any advice could my body be detoxing from BC am I unable to conceive what’s the issue