You can get a very good $30 pack at Army surplus stores if you ask the clerk to direct you to the waterproof Swiss Army pack. I've had mine through many rainstorms, it has been thrown off trains, sat on, etc. and not once has anything inside ever gotten wet. And it's still in pretty much the same condition about 8 years later. Not to mention, the weight distribution is infinitely better than with Alice Packs and it is just as comfortable as any $200 REI pack. It has full lumbar support. Ask around and go to a few stores if necessary. I would never use anything else if I could help it.
As for "starting out" stories, I left at 17 because this kid from my high school stole a bunch of money from his parents and wanted to go on a trip. He wanted to take a bus to a friend's house in Pennsylvania but I was like fuck that. Let's go to Manhattan!! So we ended up floating around Times Square for awhile until someone directed us to Tompkins Square Park, the central location for squatters and travelers. I had no idea that kind of culture existed and was completely enthralled. But the first couple days were really rough because we had no idea what to do and ended up sleeping outside in the rain with no blankets. Finally some of the squatters took us in and taught us how to do things properly. That kid I was with went home after a few days. It took me awhile to learn the ropes because I was very naive then and people were constantly trying to take advantage of that. Plus I was way too into being intoxicated every single day so this really held me up in a lot of ways. Now I'm back on track, making art again and very motivated. I now wish I had used all that free time to draw some of the people I met or some of the beautiful old abandoned churches/factories I stayed in.
People here have given you some good advice, especially as regards running away from your problems. It's easy to think there are no consequences when you're in a different place every day--but believe me, this is just not true. There are lots of ways to travel while still being productive so try to find a way to do that if you can. Life is better than you think. Good luck!