Hmmh.
I think the fact that you are not so comfortable in itself is cause for worry.
Before you allow him in on this, subtly try to feel him out(with leading questions here and there) to know his opinions and stand on certain things that will point to his values to see where he is on them.For instance, if he values education/personal development over hangouts/partying/clubbing in the short term basis, that will let you in on his expectations & beliefs with regards to delayed gratification versus immediate enjoyment.
If his values and your values mesh, then knowing how much you earn will not be a big deal (be it underwhelming as of now or on point).
So tease out his value system and other things will most likely add up.
Goodluck on finding that out.