Ejaculation inside the vagina

My boyfriend and I are very sexually active, have been for about a year now. I’ve been on birth control pills for the past couple if years and since I started seeing my boyfriend, I have been very good about taking my pill on time and without missing any days.

My question is, if my boyfriend ejaculates inside rather than pulling out, will it increase my chances of becoming pregnant? A doctor from planned parenthood said it does not increase my chances at all, but that just sounds so hard to believe and also I wanted a few other options or for someone to explain to me how that’s the case!

Thanks in advance!