Long as shit post on its way... Bear with me... I'm making things up as I go along... Well... Not "making things up"... Just stringing together the thoughts as they come.
In my opinion, you shouldn't have been together in the first place.
You've spent 3 years together so you're obviously committed to a long haul relationship, but getting together at the age of 15 with the prospect of marriage somewhere down the track is a bit much.
I'm not insulting you or anything, quite the opposite, most people at the age of 15 are lucky to last more than 3 months and you've been together 3 years. I applaud you. You're 18 now and I see that you have the maturity to value waiting till later in life to get married (which is a good idea).
In my opinion if you remained friends until this point and got together now, you'd be better off. Then again, I can sympathise entirely with why you didn't wait. When you have someone you really like (and think you might be able to love) you don't really want to just sit around and wait to be older. I'm 19 now... Got together with my girlfriend at 17 and decided I wanted to be with her forever around 18... We decided, like you, that marriage before university/careers/whatever is an incredibly dumb idea to even entertain and we weren't going to proceed until things were sorted. Christian faith is what you're dealing with I'm guessing? Same here.
If you've been going for 3 years well... It'll be difficult, but you've been this far already... Going further isn't going to hurt anything. You're obviously onto a good thing. Stay with it.
As for the more intimate side of things... Yeah... I can sympathise with that. My girlfriend and I didn't do anything for a good while and when we started there were several "go/no-go" decisions where we decided we wouldn't do anything further... We broke that wall many times and made new ones further. We now have a wall in place that will never be breached. Its made of Adamantium and sealed with magic and shit.
Just because she says "no" now, doesn't mean she'll say no later. I'm not saying, you'll have wild sex in a few months, you may not have sex at all until marriage, who knows? What I'm saying is that it's likely that she'll one day deem a breast grab as no big deal and its likely that she'll come to terms with the more sexually based attraction that lies outside of personalities.
Sex is important yes, but it isn't the be all and end all of a healthy relationship. Trust and friendship are whats most important and since you have 3 years under your belt I'm thinking you already have those virtues in trumps.
Stay with it if you really do love her. Things will work out for good.
