How do I know if my girlfriend is the one?

I have known my girlfriend for about 3 years now. But after us both getting side tracked we didnt get serious until about 3 months ago. My problem now is that we dont live close to each other. In fact were about 6 hours apart!! Sucks. We see each other when we can. I have begged her to move down. She wouldn't ever give me a strait answer until now. She said that she's worked really hard for this promotion she has recieved and that its not the right time. She plans on moving back down here because shes from here. I cant move there if shes movin back anyway. So Im stuck here waiting....waiting until when....there's no set date. HELP!!