I'm like that myself.
I am currently 29, diagnosed about half a year ago. Very socially isolated, hardly any work experience. Endless days of watching tv shows and browsing the internet. My brain was sort of trying to get a quick fix for mental stimulation. Jumping from interest to interest is what did it for me. I have years behinds me that are filled with all sorts of new obsessions that only lasted for a short while. I found something new that peaked my interest, "solved' the issue of how to pick up this new interest, got bored because all that was left was the execution so I jumped on a new thing that looked more mentally challenging.
During this time, I had a lot of long stretches of time where I just didn't feel. I just was. I think this might be a part of why you don't feel depressed. Just because you don't feel extremely sad, doesn't mean you're not going through a depression.
I fell physically ill, which finally gave me the authority to ask for help. I started full time therapy a year ago. Therapy will end tomorrow for me.
I can not tell you that my life will be better from now on, because that is an unknown to me. What I can tell you however is that this year in therapy gave me acceptance of myself. I got diagnosed with aspergers, i accepted that I have my limitations because of this. I learned (to some extent) that I was not as useless as I think I am. I have learned to interact with people better. I learned that I need to go slow and not rush ahead.
I have picked up printmaking as a new hobby (which I find I am actually sticking to). I plan on taking piano classes without running too far ahead of myself. I am going to try and volunteer at the hospital I stayed at. I entered a program to help me find my goal in professional life. I am actually taking steps to break through this all and I haven't felt this good in years. I am scared shitless, but I am going forward.
So for your own sake. Get help. I wish someone told me 4 years ago when I was your age. Things didn't magically get better, and I regret not getting help sooner.