bleeding during sex

I am curious as to the amount of bleeding you are supposed to have for a first time. I had sex for the first time on Thursday, and while it was a bit uncomfortable, and hurt a little, i did not bleed very much, like just a small amount that i only noticed on toilet paper. But then on sunday I had sex for the second time and it hurt a bit at the start but then it was really quite enjoyable, but then we looked down and noticed there was a substantial amount of blood, like a pool on the bed that soaked through onto the matress! At first I thought i had started my period because I am expecting it any minute, but now i seem to have stopped bleeding so I dont understand why i bled heavily the second time but not the first! How much did you all bleed the first time? Should I be worried?