Okay, so I have a suggestion - why not just try on swim suits first *without* a mirror? Then, ONLY if they *feel* really good, bother to look in the mirror? If it doesn't feel good, take it off and move on without looking.
I know I repeat it a lot, but the way a clothing item feels on my body is so important to me that I've begun doing it this way as much as I can so that I'm not swayed by a pretty color or style if it's not going to feel good wearing it for hours.
And most swimmers have very muscular thighs, right? So maybe looking at the brands the professional swimmers buy would help?