Yeah, that's problematic. Danskin is on the long list of clothing manufacturers that are mostly too sheer for me. It's not exactly that you can see through all their stuff, visually...it's more about how thin and clingy the fabric is. I do wear a bra, but that doesn't mean I want the little hooks and stitching details to be clearly outlined by my shirt.

I'm not sure if Scott's mother forgets that I don't wear a bra or if she's trying to make me wear one by continually buying me things I can't wear without one.

If she acts in good faith at other times, she's probably acting in good faith about this, too. (Or if she's a passive-aggressive manipulator about other things, you have your answer for this.) Most women wear bras at least some of the time. And it seems increasingly hard for me to find shirts that are both soft and substantial. Most of them are sheer, or clingy, or stiff, or scratchy...I often give up and just wear layers.

Consider if it's worth wearing as an underlayer? It can be useful if it's comfortable against your skin, and the outside is smooth enough not to catch against your dress, and it doesn't have a collar to get in the way. It doesn't need long sleeves to help keep your core warm.