I'm seconding Printables - you can upload both stl and step files there, they have a nice UI that's easy to navigate.
As a side note, have your considered starting a Patreon or something with your 3D models? If you make some good models (and you seem to know what you're doing), it might help towards your goal of getting 3D printer sooner. Though it's probably hard without a printer to test it on, I guess.