16, in a relationship, and confused about mixed messages on sex

I'm 16, a virgin, as is my girlfriend who I've been dating for ~2 1/2 years now. We've messed around a lot, but haven't had full-out actual sex. I'm willing, but she says she feels like she isn't ready yet.

Now, I understand her position, and certainly respect it. I try not to pressure her into doing anything she doesn't want to, but it's hard when it feels like I'm the odd one out in this case. I realize that being a 16 year old virgin is absolutely nothing to be worried about, it's not like I'm in a rush to lose my virginity. What I am wondering about is the 2 1/2 number. I look at my friends' relationships and it seems like anyone dating longer than 7 or 8 months has had sex. Add in the message from Hollywood and music and it really starts to feel like I got completely shafted when it comes to sex.

I guess my question is whether or not what I'm feeling is normal or justified. Am I just too young to have sex anyway? Is it really less common than it seems, even in relationships this long? (long for a 16 yr old at least) Or am I just unlucky and need to suck it up?