Scared of sex because of questioning sexuality...

Hello everyoneI'm 19 and a virgin. I have been questioning my sexuality for a couple of months. Recently I was sort of in a position to have oral sex with a woman and felt scared. Thoughts and anxiety popped into my head. "What if I don't get an erection?" "What if the experience is bad?" "What if this confirms that I'm gay?" Is this common and how should I deal with this?