Is it normal to want to suck cock even when guys don't turn you on?

Very normal. Lots of men don't have an emotional or romantic attraction toward other men but are interested in sucking their dicks. Guys absolutely don't turn me on, but I really enjoy sucking a cock. You're right at the age where you would explore this type of interest. I would suggest you find a guy you're comfortable with and try it.

Absolutely this is normal. If you ever find yourself on your knees in front of another guy, you'll find yourself zeroing in on his dick with little thought as to his overall physical appearance, and without any emotional attachment to the person himself. Cocksucking is about the dick and the dick alone, in most cases. Once it's in your mouth, you won't care who it's attached to.

Don't let it bother you... you sound bi-curious.

you my friend are one very sexually confused guy... maybe you should reconsider if guys turn you on