Vaginal Bleeding During Sex

I've been with my boyfriend for about 19 months. I have sex frequently, usualy 1-3 times a day. We have had threesomes but stoped because last summer me and my boyfriend got chlamydia. I went to the doctors and it was handled quickly, I took some antibiotics. Later tests proved that I didnt have it anymore and still dont have it. About 3 months ago while having sex I started to bleed. This bleeding was a bit brighter red then my period. I always have enough lubrication. We do have very hard fast sex though. Everytime since then when I have sex I bleed. A month ago I went to my doctor and took a piss test. I showed negative for bacterial infections, chlamydia, pregnancy, and etc. She switched my birth control pills and told me to come back in a month to check up and take a pap test. Well switching the BC pills didn't work, and I take them everyday at pretty much the right time everytime. There is no pain when I have sex, mayby just some mild discomfort in my abdomin after but nothing to serious and I'm not really worried about it. Idk if I should be. I've been trying to stop having sex for a while to see if itd help. I stoped for about 1 week. When I had softer gentler sex I didnt bleed. But when I started having harder sex it started bleeding again. Idk what to do please help. Does anyone know what it could be? My doctors appointment is in 1 week but I wanna have a general idea of what I could have. I've been trying to stop having sex till then but its really hard for me. I need to have sex! But I want to get better.

Thanks