Unfortunately not ... As you yourself said, the repository is private, so if you removed it, github disregards all your contributions to it.
However, you can continue to contribute to open source code! It's a great way to learn, and it will not be removed from your contribution list, only if the project is deleted (but your fork will stick). Remember, number of contributions is not a metric for software quality or for the skill of the programmer, for example, I can do 5000 useless commits while another person can solve a big problem in just 1 .
A good programmer is not one who has more contributions, but one who knows what he is doing and likes what he does.
Welcome to StackOverflow PT!