'Kay I know my gender marker is M here but I still wear sports bras + don't want them to be seen... I've got one good one, and it's hard to tell looking at it why it doesn't seem to poke out under my t-shirt - the only thing I can think of is that it's lower cut. Even though most of them seem to be racer-backs, they're not all the exact same shape. The thing is, there's no way to tell until you try it on... You might want to order a bunch (scary for the bank account i know) and try them all on, and then send back the ones that don't work + get a refund. That's how I used to find regular bras that fitted too.
Also looking for low-impact ones, they tend to have thinner straps more like a normal bra.