i wanted to wait till marriage when i was younger (didn't we all, haha), and then i was with a boy who loved me very much, and after 8 months of dating and heavy petting/oral, i decided i really, really wanted it. one day i just woke up like "today i will have intercourse". it was totally weird. i was completely at peace with the fact that i was giving myself to somone. it went from "losing" something authentically and preciously me, to "gaining" the experience of sharing it with someone. i was 18. so we did, and it was probably the BEST hetero sex i've ever had. it hurt a little, but i didn't notice it. it's so emotionally and physically powerful, it was just a trivial by-product. but that was me.
a friend of mine was the opposite. she wanted to wait for the same reasons as you. she lost her virginity at, i think, 22. for her, it was all about control (admittedly). fear, but mostly control. depending on how you look at it, losing your virgintiy is giving a lot of control to someone else. emotionally, physically, etc. on the other hand, it's giving a lot of control to yourself. control over your sexuality and desires.
don't do it with the guy your with or the next guy that comes along if you do not feel completely comfortable. not just comfortable, but resolved, excited, optimistic, safe.
also, don't not have sex with a man because you feel like he doesn't "live up" to superficial requirements. the size of a man's penis, how good-looking he is, his body's appearance all have little to do with how he is in bed.
i wouldn't do anything until ready, but i would simultaneously contamplate the reasons WHY you don't want to have sex. a therapist (or even a listening friend) can draw out of you the real reason you are afraid, whatever that may be. we often don't realize why we're afraid of things, love thing, dislike things, hate things, and discovering that (and it really is "discovering") can send you on your way to dealing with it and having a great fulfilling sex life.
masterbate! masterbate! masterbate! masterbate! masterbate!