Orgasming

I’m 18, and I’ve never cum before.

When I “masturbate” it’s kind of more of a matter of getting turned on.

My boyfriend has touched me and fingered me a little, and I’ve gone down on him once (I was on my period so I didn’t want him to go down on me).

Next time we hang out he’s offered to go down on me, and I really want him to, but I’m nervous that I’ve never cum before and I’m scared I won’t, because I want to.

I won’t fake it because we’re really big on having good communication.

I guess I’m just scared because I don’t know what to expect?

Any advice or input would be much appreciated.