Is it okay that I am bleeding during Sex ?

I lost my virginity in may this year. I have recently started having sex with my boyfriend . We have had sex 3 times this week. Thursday night, Sunday night and then last night. The first couple of times we did it, I did not bleed but this past time we had sex I started bleeding during sex . I just wanted to know if it was normal to bleed during sex and if so , what caused me to bleed? I am new to sex and want to make sure I am okay. my boyfriend's dick is really big so I have no idea if that has anything to do with it.