I'm Autistic so I don't use the word obsession lightly but regardless of what you care to call it, what things did you love as a child?
Books were my main obsession. I almost always had a book in my hand and when I didn't I'd read cereal packets and shampoo bottles.
Insects and wildlife were others. I had a bug hunting kit and I was always looking for different species, particularly spiders, which I adored and still do.
Horses too, as is true of many girls I think.
Later I loved Boyzone, BSB and other boy bands. Then when Riverdance became big it and Michael Flatley became another obsession and my Tom Cruise phase started about then too.