Bitter Vag

So my boyfriend tells me that when he gives me oral, my vag tastes bitter to him. 
We've never has sex with anyone else before we got together, so when he does try to go down on me orally, he just really doesn't know what he's doing. 
I don't know if it's me, because apparently I taste bitter, or its him because he's much happier just fingering me (which he is very good at)