I'll probably get screamed at by a few for this, but the simple truth is that if you're serious about getting into the games industry (which I think it's safe to assume you are - you're here asking for help and you're asking about game engines, no?) then you need to be highly competent with C++. There's no two ways about.
If you're wanting to get into programming in general then yeah, you can afford to be a bit more expansive and study other languages. But honestly I'd just dive right in and get going with C++. You said you had the most experience with it so why not carry on from there?
If you're unsure where to go from your current abilities, why not tell us the sort of stuff you understand so we can point you in the right direction? There's the standard drivel of programming requiring dedication and time but in my eyes if you're suitably passionate about it (your history with C++ at your age suggests you are) then you can ignore all of that and just drive onwards with your chosen language.
Best of luck whichever path you go down dude
EDIT: As for engines.. Don't think about them until you're competent with C++. Apologies if you are - if not, get going with some 2D games. Knowing a language isn't enough sometimes - you need to understand game structure and stuff alongside it!