As other's have mentioned, I started off about the same way as you. I didn't drink until my Junior year and it didn't become a regular "habbit" until my Freshman year in college. That is the time I started with the pot as well. For me it never really progressed beyond those two drugs, however that did not stop it from becoming a MAJOR problem in my life. Over the next 20+ years of pretty much constent use, I managed to loose just about everything of meaning in my life. Over the last year I've managed to get my life back on track, but not before losing my wife, hundered's of thousands of dollars and almost my life. I'm 41 now, and feel like I have pi$$ed away half of my life. At least I didn't lose the whole thing.
I agree that only you can really tell if you have a problem, but obviously your gut is telling you that you do, or you wouldn't be posting here. I just wanted to point out that even if you drug and alcohol use never progresses into "hard" drugs, it can still be a major problem. You might want to take a careful look at why you choose to use like you do. There is frequently some kind of driving motivation behind wanting to be f'd up all the time.
Welcome to Sober Recovery. A great place to learn, ask questions, and maybe even help some other people out. Take care.