is this normal?

So I'm currently sleeping with this guy, I found out that for 5 of the times we slept together I was ovulating and we didn't use anything, we had sex 8 times. I started to bled yesterday, it was different, it had little bits in it? But I'm not due on until 2 weeks and I'm always on time. Today I was heavily bleeding, like my normal period. The guys sister told me to get it checked out but I'm sure it's nothing?