Most of the time, a git repository is responsible for storing one single project. If your project depends on another projects, you can use git submodules.
From what you described, it looks like you are developing multiple separated projects but I wouldn’t recommend pushing them to the same repository except if they are composed of more than one file, which in this case it will be better to split the projects.
Are your projects contained in single .pde files or you are using an IDE like Eclipse to develop?