Re: sexual health and losing virginity
Listen, I know several guys who are 21 or 22 and still virgins, with varying degrees of sexual experience ranging from none to "everything but". It's more common than you probably think.
From my perspective (21 year old female), I wouldn't care a bit whether you were a virgin or not. If anything, I would feel kinda special if I was your "first". So relax, it won't affect your potency or sexual peak either.
When you're talking to a doctor, by the way, you answer "no" to the question about being sexually active if you just masturbate, since it doesn't really have an effect on your health.