I get my KN95 masks from this site that was mentioned in a NY times article earlier this year regarding where to get quality masks.
https://bonafidemasks.com/
The Powecom KN95 ear loop masks are fairly large. One family member and one friend who tried them thought they were large for them. I have a fairly large head and my face is on the wider side of average. I find the masks fit me pretty well. I just need to make sure the area around the nose is formed correctly. I have some headband style ones too but have not tried them.
Regarding the tight headband fit. Have you tried stretching out the headband? I’ve seen some reports of that working. Use one hand to pinch down and relieve stress on the attachment point and the other hand to stretch the band a bit.