Hi there,
I can relate!
I have always had interests drift in and out of my life. I played an instrument for 10 years, I took tennis lessons for four years, I was really into parakeets for a while. I collected rocks for a while, then Beanie Babies.
I am not involved in any of those hobbies any more, and different ones have taken their place. I'm sure that some things I enjoy right now, probably won't matter as much to me in years to come. There have been a few interests that remain the same, and occasionally I'll pick up an old one again, but really it's like pulling cards from a deck and putting them back when I'm done. I don't see it as anything bad, I see it as having a full and interesting life with lots to keep me occupied.
I don't think that in itself is a problem. Interests can come and go as we grow up and change as people. Personally I think that it's really cool that interests change - in a way, doesn't it show that we're changing and growing as individuals, enough so that what once fit us, no longer captures our attention?
However, it sounds like the intensity of your pastimes (also called hobbies, interests, activities) is possibly what upset you? I can understand that. It sounds like the above posters have given some good advice if you want to pursue the possibility of having autism.
More than that, I guess I could suggest you seek balance in your life. Make rules as to how much money you're willing to spend on a hobby, or how many hours you can play a game, and periodically reward yourself for sticking to them.
Frankly I might spend a weekend binging on video games, but it helps me unwind from a busy life, and as long as it's not negatively impacting anything, it's okay. I think you are okay.

If you choose to pursue the possibility of getting diagnosed and making some changes to fix the issues that come from your "obsessions," then I wish you the best of luck in finding the support and care you need.