Pain during sex

So I've been having sex for a couple years but I just realized, I might be having painful sex that everyone tells you to look out for as it could be a sign of something else. I've been ignoring it this whole time because for some reason I was kind of just under the impression that all sex just feels like this because I'm a girl, but penetration is painful in certain positions where my boyfriend can go deeper. He isn't even big, and I've always thought to myself that I'm glad I'm not having sex with someone who has a bigger penis because I would probably die. But I have to stop him in some positions because it hurts, I've always thought it felt like he was just hitting the end of my vagina and reaching my cervix, but is that still not normal? I haven't thought about going to the doctor because I can still have sex, but a lot of time I want him to finish fast so it can be over. I do get wet and turned on enough so dryness etc isn't the problem. Is the kind of sexual pain that needs the doctor? Is this a warning sign of endometriosis?