Bleeding after sex

I’m 18 and I had sex with my boyfriend twice. Both times after we have sex I bleed a lot. Like I have to wear pads for a few days. I know it’s not my period because my period come separately from that bleeding. Is it normal to bleed after sex or any advice on what I should do? Tbh I think it’s because he penis is really big. He is like 6’5 and I’m like 5’4 so do that math. Anyways please help I’m really worried and I’m scare to ask my mom for help