I am not a teen, but I had a similar experience when I was your age when Facebook was first a thing and Google was becoming known for its privacy issues etc.

I'll just say this; it's a great feeling to google your own name and having absolutely nothing come back. Obviously there's bound to be data about me somewhere out there, merely interacting with the internet exposes data about you (ex. You can be identified by your unique writing-style), but your personal data is one of those things that gets released in degrees and each bit that escapes is something that can't be put back in the bag once it's out there.

I think the best we can do if our interest is in preserving our privacy is to consider it a best-effort endeavour and make any compromises consciously when we personally judge the return on our data's value to be fair.