I'm a Girl Who Loves Giving Head But......

I like to please my boyfriend by giving him oral sex but I have a problem.
My boyfriend has alot of precum and I really don;t like the taste or texture being in my mouth. I can't spit it out because I even hate it on my tongue. I tried doing it in the shower cos then if I did spit it he wouldnt notice but it still tasted yuck. The worst part is even though I enjoy pleasuring him I still gag if too much enters my mouth..Please help me!!
I feel like we've tried everything. Is there any way to stop a guy from getting precum or limiting the amount that comes out?