What Could Cause The Bruise In Vagina After Having Intercourse?

Hello, I have been having missionary sex with my boyfriend, non-aggressive. I have a small bruise on the bottom of my labia, near the vaginal opening, and a small tear directly below the opening, where the labias meet. I am petite and he is not. I know bruising/tearing occasionally happens, but I want to know if there are any concerns with more regular bruising/tearing. My vagina doe not seem to be adjusting to his size/firmness. We have sex approximately once every week and a half or so.