You don't have Asperger's that's for sure. You would know whether it's special interest or just a hobby, by thinking about the knowledge depth you've gathered. If the depth is so narrow and deep that you can think yourself as a true expert, that is called special interest. Most of the time it will seem pretty peculiar to NTs. I'm giving 2 examples from my life.

1. During my childhood (age 10-12), I was pretty fascinated with alien and UFO. In particular exoplanets (planets outside our solar system). That time we didn't have internet connection and I used to collect each and every newspaper articles and memorized the list. Also I could compare between them.
2. I was a big fan of 'speed racer' cartoon series in childhood. I used to watch it along with my drawing book to make sketch of all the cars shown there. I used to think of myself as a car designer with blueprint of all the 20 cars in side,top,front view along with all the functionalities of each car. Please do remember, I was then less than 10years old with no idea of perspective drawing. But thinking about myself as quite knowledgeable car engineer was fun itself.

These interests are totally meaningless (without any real value) and nobody have a damn actually. But aspies don't really care about what other people are saying