Hi there Max,

I too am of the same age, and I too am fascinated with math. :)

Now that I think about it, I was inspired by two teachers and two books.

1. The first book was a pretty old one called "Elementary Mathematics" by three Russian authors called G.Dorofeev,Potapov and Rozov. These books were published by a publishing company called Mir Publishers. They used to print extremely good books which were available for a pittance a couple of decades back, but they have shut down now after the collapse of the Soviet Union.
2. The second one was an Indian book called "Challenges and Thrills of Pre-College mathematics". You might be able to order that if you try hard enough.

Another one I recommend is "Men of Mathematics" by E.T.Bell. This is a well-known classic, and I'm reading it now.

All the best for your future and I hope we meet someday in the math world! :)