I disagree with your first point, when I started learning c++ I wanted to make an integral approximator, an approximator that takes any function and returns the approximate value. I already knew programming through java, and I'm not entirely used to the C++ syntax. Basically what I did to do my programming project that was "fun for me" was rush through the learning process, skipping detail of classes, inheritance, polymorphism, structs, linked lists, pointers and arrays, to get to lamda functions. Eventually I did get to learn c++ formally with my programming class, most of which I don't remember learning it during the summer. Its not that doing your own projects is bad, you just can't be overly ambitious on it.