From memory (it's not very good at the moment, preggy brain and all) I have never had matching bra and undies. No matter what age or size I was. I never saw the point in it. If I'm fully dressed no one would know, and if I'm getting comfy the bra is off anyway so it would just be for myself and as I said I don't see the point.

My fave undies are string bikini's. They are the most comfy (and I've tried them all over the years), but they are not all that easy to find. They are stretchy on the string bits on the side so they feel great - look like a g string from the front, a bikini from the back without the "wedgy feeling" you can get from a g and without the risk of infection.