As someone who was in a committed relationship from the ages of 17-22 my advice would be to seriously evaluate if you want to be married at your young age or not. If not you're not doing yourself or your girlfriend any favors.
I still look back on that time of my life filled with regret for missed opportunities. She was a great girl but that time of your life is about becoming who you want to be and that's damn near impossible in a relationship.
If you two are meant to be together it will happen regardless of what you do.
If you still want to be sure drink a gallon of water the morning of the test and pee as much as you can before you go. The result will be "negative dilute" and you will be re-tested but a second negative dilute equals a pass.
You shouldn't need to do that but if you feel the need it will work.
***this statement may or may not be made by someone who did exactly that and started a new job recently.
...is awesome!! Sweet office with one wall being a window, not just a window, the whole freaking wall is glass. Near the airport so I get to watch planes take off all day. Super laid back and cool people. Learning a lot about anatomy and surgeries. Yes I had to brag, carry on huddle.
Focus on one instrument to start, and don't pay for lessons. There's enough info on youtube for you to get the majority of the basics out of the way.
Music is instinctual, and if you have an innate ability to play it that will come out on its own. It may not happen right away, but if you can stick with it you will get there.
Lastly, guitar players are a dime a dozen, so only learn that instrument if you get great satisfaction out of playing it. If you want to get into a band and play in front of crowds learn the bass or drums, those players are always in demand. Trust me, music touches your soul, and the only thing more gratifying is when what you are playing touches other peoples souls.