I'm in a different situation than you. My main interest right now is hockey, but with NHL season closing down. I need to find a new interest pretty soon. I don't spend a lot of money on stuff either, just kinda of soak up information.
As for a way to change... there's really not a whole lot anyone can do really.
It's the same for people who don't have have autism too, some people can have one interest that lasts for a while. While others change constantly, but my problem is that my interests are pretty random case in point * a while back I had some interest in Vikings * don't get me wrong vikings are cool, but when will a conversation start up for vikings in the modern world. 
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" If I did THIS... would that mean anything to you? "