If your shoe size hasn't changed, I'd recommend trying Rothy's. Caveat: they don't really offer arch support if you need it, but a lot of people have said they order up a size and then buy an arch insole. I'm not usually the type of person who gets hooked on brands, but they are, by far, the most comfortable flats I've ever had, and worth the investment. Plus, you can get $20 off referral codes from just about anybody. I typically have a problem with flats rubbing the back of my heel, and I have not had an issue with these at all. They're sustainable and washable.