Did i lose muscle mass?

Absolutely not man. I was 146lbs like 3 weeks ago, but now I am 140 and I am way stronger. I have just cut a lot of fat. My waist is 29.5 down from 31, my lifts have all gone up by like 20 percent or more since I started- Bench 95 up to 125, chin ups 5 up to 11, press ups 20 up to 30 etc etc. How tall are you? You have probably just lost some fat so that is good, the muscle comes later. So if you are lifting more you clearly have more muscle regardless of weight loss.