Funny, I have had the cup curling issue with a couple of bras. I am very much like you, in that not only do I like T shirt bras, but they have to be the smooth, silky material, as opposed to the more meshy, lace edged stuff. I cannot stand the feel, and they feel very tight, even in the correct size. I live close to a real lingerie store, and when I told the person there I couldn't stand the material on certain bras, she thought it was weird. She said the band should be tight... I hate that, because it itches me. I have found a couple of styles that meet my requirements, though.
I stopped buying bras on line 10 years ago, when this place opened up. I often joke with them, that I am the only suburban woman of a certain age that buys a certain brand of thong and bra, both of which they stopped selling. Last year, before my ski trip, I went in to buy a couple of more sexier type night-wear things. There was a new sales person, who was about my age (the owners are young) and she showed me stuff that looked worse than what my grandmother wore... however, I did find stuff I love. It's just funny that almost every brand of product I've bought and liked has been discontinued in the store.