Hey my good man, there is a girl that I met and knew well in this very site. She hooked up with a guy for a very short time, had lots of sex---fornication, the works. Guess where she is right now? Serving a mission. 6 months after she broke it off with this guy she was on her way. She didn't spend lots of time berating and flogging herself over guilt and misery. She put it aside, went through the repentance process, and is now doing what she so desired. It seems you are making more of your "sin" than is called for. Get it "hence" and get on with your plans. As for your gf you're going to have to shunt her aside for 2 years----may as well get started and get used to it. And a little growing up might do wonders for you as well.. Much luck to you Elder.