I had something similar happen to me. But it sounds like my teacher handled it differently. I used to watch a lot of documentaries. There was a public access TV channel that would air educational content, I'd occasionally watch it for "fun".

After watching a documentary about Conic Section I asked my math teacher "When are we going to learn about Ellipses and Hyperbolas?" This was in year 7 (so age 12/13), We were learning about perimeter and area at the time I found it dead easy.

He patiently explained to me that we needed to build up to those topics and it wasn't something we could just skip ahead to. looking back on it I think he handled me pretty well. He didn't discourage me and he justified things in a way that 12 year old me could understand that there was a reason we covered the topics in the order that we did.

Conic sections would end up being taught in 11th Grade when I was 17.