Hi Ryan, to be honest, I think a lot of what you're feeling is largely due to the distance. Your relationship isn't meeting your physical needs. Not just sex, but cuddles and kisses and holding hands. And at your age, wanting lots of sex and physical contact is pretty normal.
I also have to comment on the two of you often arguing about the things you disagree about. Mate, as much as you like to think it's normal - truth is, this doesn't belong in a good, healthy relationship. You see, in a good relationship, you'd get it sorted out once and for all and quit fighting about the issue. If it was something you'll never agree on, then 'agree to disagree' is a good answer. But either way, rehashing the same old shit isn't good.
Have you considered that the grass may actually BE greener? It's Ok to recognise that sometimes the person we are with simply doesn't suit us. This is especially common when we're in our teens and early 20's. You'll change heaps and your outlook and what you want from a relationship will change too.
I'm not telling you to up and leave. But please do sit down and really think about the pros and cons of being with this girl. You've mentioned some great strengths, but if this relationship was really perfect for you, I doubt you'd have this itch to scratch. Give yourself permission to question whether or not this really suits you.
Never regret anything that has happened in your life. It cannot be changed, forgotten or undone. So, take it as a lesson learned and move on.