Nexplanon

So i recently got my nexplanon out two weeks ago, i had sex 6 days after that. What are my chances of becoming pregnant? my periods were irregular before i got on the nexplanon, and i had cycles while i was on it. I had my nexplanon for almost 2 years. But my doctor told me not to have sex without a condom because i could get pregnant but i’m not sure if i’m able to conceive or not because i’m never got pregnant in the past with my boyfriend and we’ve tried.