:cry: Learning a language IS challenging and difficult, especially if you're not in a situation where you are forced to use it.
One of the things I have learned is to to use it as often as possibly, even if a sentence is grammatically mistaken, or some words are missing, just keep talking as many Japanese people as you can.
Also, just like we all learned to speak out native language through listening as babies to our parents talk...it's very important to listen to a variety of Japanese talk. Like- TV shows, they usually speak the colloquial daily language. Once your ear is able to catch phrases - I believe you will be able to imitate them, and eventually use them yourself.
Having someone to learn with, is a major bonus. You can motivate each other and challenge each other, so have fun learning Japanese with your girlfriend! :lol: