could I be pregnant? help !!

elana • I love my dogs

my period should be starting pretty soon, but I haven't experienced ANY pms symptoms (I'm literally supposed to start in two days). I've never experienced any pregnancy scares, and I'm only 18. however my boyfriend and I have had a few unprotected sessions. he's supposed to be infertile and my uterus is tilted at a weird angle and I'm supposed to have problems conceiving, so we didn't think not having a condom would be a big deal. I was just wondering how long after having unprotected sex are you able to ACCURATELY detect a prgnancy, and how long after will some symptoms begin to show. I know there's a slim chance I'm pregnant, but I want to know what and when to start looking for signs. I hope this made some sort of sense !! (please don't be rude I can't ask my parents about this because they don't know I've been having sex with him. )