breast pain but not sure why

I'm a little worried cause I noticed that my boobies feel more sore now, well ever since i started being sexually active which is bout a month ago, and I'm trying to figure out if it's cause he grabs them really hard when he's horny or if it's cause their growing cause of sex (if that's even true😂). i know theres litteraly no chance im preg cause we've neverrr had sex w/out condom and it never broke. so does someone maybeeee know, how achy your boobies have to feel in order for it to may be breast cancer?!