Keep in mind that clothing sizes, at least in the US, are not consistent. You can get three pairs of jeans in size 12 from three different manufacturers, and I can guarantee that like the Three Bears' chairs one pair will be too big, one pair will be too small and the third will be "just right."

As far as your relatives' comments, if you've been heavy for a while it's tough to connect how you are now to how they're used to seeing you. I have a cousin who had gastric bypass surgery a couple of years ago. She's lost a tremendous amount of weight, but there's a part of me that still sees her as heavy (it doesn't help that like most GB patients I've met she looks like a deflated human-shaped balloon and VERY unhealthy). However, I'd never dream about asking her how much she weighs or what size she wears. None of my business.