I was going to tell you to go on Amazon but a poster has beaten me to it. I had very slim legs but following an accident resulting in heart problems and horribly swollen legs I couldn’t wear any knee highs at all. My diabetic nurse told me about a site which supplied tights, stockings and knee highs and was genuine, always a concern. I am an Amazon customer, I’m the one who ensures they will never go bankrupt, so if you do that and put in the little box, ladies extra large knee highs you will see a selection.
I have no connection with Amazon apart from being a customer and I am not touting for business just trying to offer help for a problem I understand.