I think perhaps you're trying too hard to find something you like and trying to find something you will immediately become interested? Sometimes when you look too hard, you may feel like you can't enjoy something because you place pressure on yourself to "like" something straight away.
I think "obsession" might be the wrong term here, because it sounds like you are referring to an interest in which you can take an avid interest. Maybe "intense interest"?
Anyways, from my personal experience, my intense interests have happened without me even realising it. I'm currently very, VERY interested with a game called Anarchy Online, and I never intended it to become an intense interest. I just wanted to play an online game because when I first started with the game, I had just obtained broadband, I'd never played an online-based graphical game before and AO was available for free. The "intense interest" thing just happened.
So maybe you can relax more and try to enjoy some activities...who knows, maybe you'll stumble onto something which will have your intense interest.
I'm not a health professional, but if you are still concerned at your lack of enjoyment in activities and life, it might be worth speaking to a doctor about depression [if you haven't already].
_________________
Said the apple to the orange,
"Oh, I wanted you to come
Close to me and
Kiss me to the core."
Think you're ASD? Get thee to a professional!