I would upload then private my videos because I don’t see any progress
Firstly, don't do this. Some videos don't do well at the start, but maybe pick up about a year later. My most watched videos are over a year old.
It seems that you need to be a bit more patient. Youtube isn't a sprint, but a marathon. Put out content consistently (at least once a week), have a clear niece, hone your titles and descriptions, make good thumbnails and tag correctly. After you all that, you can start thinking about promoting it elsewhere.