That's how I've felt for the greater part of my life. I still do sometimes. Except now I have my family and friends, and that helps when I feel like I dont amount to anything else. The purpose of life doesn't have to be some huge, looming thing. It can be little things everyday. It can change and mold to what's going on. It can be how you treat people, and make them feel like they matter. Right now, doing your art project, I'm sure that as you share it, it's helping others too. So your life never has no purpose. Your passion can be whatever helps you to get through each day.