I'm ttc while bf is maybe?

Avery
I'm 21 and my bf is 25. We've been together for 2 years and met at work(we are both servers). Were both madly in love and talk about settling down, getting careers, and starting a family.  
​ We've agreed that we both want to "not try to not have a baby". we've always used the withdrawal method and are very successful with it. Only problem is he still withdrawals instead of ejaculating in me?! He says it's just habit and can't help it. I've been checking my cm and we've been having sex every other day (multiple times on my fertile days). BUT HE STILL ALWAYS PULLED OUT. What are my chances of conceiving if he's still withdrawing?