Help me please

I gave my bf head 2x I'm hos forst same as me hes my first everything.(sex and bj) I just wanted to knwo cause he does finger me and a but he sometimes ask to eat me out and like I want him to but I also dont want it to be gross down there I mean I clena it really good and etc I drink loads of water but also at same time sometimes I bleed but I'm on birth control so idk y

Any reasons why Can be?

And also some tips and tricks to do before I do let him eat me out....