I'm taking crestor (rosuvastatin) and my cholesterol readings are way below normal. My ratio is 2.1. I only take 10 mg daily. Is this okay?

Yes, as long as..... Yes, low cholesterol levels due to Crestor (rosuvastatin) is perfectly fine, and actually preferable, as long as there are no side effects and no issues with the liver (due to the crestor (rosuvastatin).).
This seems fine. If your total cholesterol is low and your ratio is as good as it seems (2.1), as long as you don't have side effects of Crestor (rosuvastatin) like muscle aches, etc., you are doing well. Keep it up.