Like the girl above me, I'm new yet feel compelled to respond.
If your doctor says you don't have an infection, then everything is fine - that's just how your body is! And your boyfriend should really understand. I personally would NEVER give oral to someone unwilling to reciprocate, and I certainly wouldn't request/demand something I wasn't willing to do in return - fair is fair!
As far as the discharge goes (as others have suggested) try drinking more water and eating more fresh fruit and vegetables. Diet and hydration can have a huge impact on your girly bits, along with everything else!
I know it has been a while since someone commented on this, and hopefully something has helped - but I thought I'd offer/second some suggestions.
And you're a smart girl for refusing to douche - the vagina cleans itself, and by douching you're destroying it's carefully cultivated environment.