Spotting after sex

Just wanted to read about some of your experiences or thoughts about this. Nearly every time after my husband and I have sex, I bleed. It's nothing too too crazy, but it keeps happening and I'm getting concerned. Or maybe it's just me overthinking things, I don't know. Most times I don't feel pain or feel he's too deep, yet I still bleed. It can happen when I'm nearing my period or not even close...I go to the doctor regularly and nothing has ever come up. Usually it would only occur if I had sex from behind with him, but recently it's even when I'm on the bottom. Hope there's someone out there who has experienced something similar and may have some insight. Thank you!