Curiosity killed the cat, innit?
Highly inquisitive and creative types are often quite vulnerable to the perils of drug use. It's instilled at birth through the passing of certain genes. In the naivety of childhood it manifests itself as a strong urge to create or learn and understand new things. These types of people are usually never satisfied and keep on pushing themselves to receive bigger endogenous rewards. They live for that rush of β-endorphin that accompanies each Eureka moment! The dopamine that motivates them to create music & art, and the added pleasure which is received when they are appraised for their good work. Then... Puberty! You want to experience new things, just like any normal inquisitive person would. You're probably considered a bit different, but are taken under the wing of the "in crowd" because they can't quite figure you out, but know there's something worthwhile in that brain of yours thats good to be around and interacting with. It's only a matter of time before you get stoned, and are blown away by the way it affects your perceptions and the ability it instills in you to conceptualise new and abstract ideas, most of which turn out to to be complete and utter stoned nonsense. But it doesn't matter, because there's that similar feeling you felt as a child when you were learning or creating. Each new drug you try takes you down a different path, each with its own rewards and insights. Pushing the baseline of pleasure/satisfaction to new highs. You start to realise the passion you once had for learning and creating is diminishing, no longer filling you with that same sense of enjoyment that it once did. Fuck it, I'll do some drugs then come back to my work later. But the more you entertain that lifestyle, the quicker the flame burns out. Suddenly you find yourself not coming up with the ideas you once had, you find it harder to retain information. Not like before when it came effortlessly. Somethings changed, and now you are only left with the odd flicker of light.
tr;dr Less drugs, more creating. And as for the girlfriend thing, hold on in there dude and keep up your good work, in the end it will pay off bigtime. :]