What Causes Light Vaginal Bleeding After Having Penetrative Sex?

Dear Doctor, I would sincerley like to know what it is I'am currently experiencing. I had gotten close with my boyfriend recently and he inserted his penis into my vagina and made slow movements. He did not fully penetrate, however i noticed a slight very light pinkish colour on the sheet it was very less and hardly noticable. We did not do anything thereafter as I was suprised. I have read about the Hymen and its location and want to find out if there is a possiblilty I may have broken my hymen with such slow movement to the vagina I'am really concerned. If it means I have does that mean I will never bleed again during intercourse as I hope to. I 'am also on the pill if that is of any relevance but due to reasons of having PCO's. Please inform me if any of this is related. Thank you