Don't know if I'm orgasming????

Okay like I know it feels really good and I moan but i don't know if I'm orgasming? I know this sounds so stupid, everything online is like "oh you'll know!" But I don't! My boyfriend has many sexual partners and knows what he's doing so is it just that I can't orgasm or what? Idk! Sorry if this is a stupid question but any input would be much appreciated!