Some people are what they call long-haulers. It can take them a long time to come back from covid.
All you can do is keep taking your supplemnts, get lots of sunshine and fresh air. Do some deep breathing exercises to try and get back your breathing to capacity.
My mom took almost a year before she back to the level of health she was at before she got covid
I was encouraged to keep using my CPAP machine. It helps keep the lungs expanded. I also have the breathing dohicky they gave me to strengthen my lungs.