Jennifer,
Just because your boyfriend has had unprotected sex in the past that has not led to pregnancy and you have had unprotected sex in the past that has not led to pregnancy does not mean that it is not possible for you to get pregnant.
If the condom broke, then there is a chance that you could be pregnant (but anytime you have sex, even if the condom hadn’t broken, there would still be a chance (granted much lower) that you could become pregnant.)
I don’t know much about endometriosis. I know that it can make conception more difficult, but it is possible to conceive even with endometriosis. Have you missed your period? If your period isn’t late yet I would try not too panic too much and wait to see if it comes as expected. If your period is late I would take a home pregnancy test to find out for sure whether you are pregnant or not. Best Wishes.
Kate