Nexplanon

I got the Nexplanon inserted on October 22nd and had sex October 27th, but my boyfriend pulled out. I’m also breastfeeding and still haven’t gotten my period back at 7 weeks pp... she said to wait two weeks but I figured I’d be okay if I’m breastfeeding and he pulled out. Yes, I know you can still get pregnant breastfeeding and still not having your period return, but I’m just wondering how likely that is??? I really don’t want to be pregnant.