Female here so I can't be much help with your sizing choice, but DON'T cut the suit. It will self-destruct. They're meant to be worn as-is. I have had to get rid of some bike and tri gear that got ripped
(because of bike crashes, snagging on things, and, in one nasty case, getting clawed by a competitor's fingernails
) and then proceeded to unravel/fall apart in stages. If you cut a tight-fitting lycra type suit, It will gradually come undone and leave you vulnerable to "wardrobe malfunction".
I also am between sizes in the
(one-piece
) suits I own. For the last suit I bought, it had me as extra-small for one measurement, small for another, and medium for a third. I went with small and it was fine. I also have a medium suit in that particular brand
(2XU
). It's on the big side--okay for wetsuit-legal swims but I notice a bit of drag in the legs without a wetsuit or speed suit over it on the swim.
As I recall, I went with chest size to order the suit, because that seemed a bigger issue in terms of comfort and performance than waist or hips. If your breathing feels constricted, that really sucks, in all three legs of triathlon. If you think the chest will be very constricting, I'd order a medium and a large
(if the company has a good return policy
) and then see if it's a tightness you can live with or not. As others have said, a tri suit feels a lot more confining dry than wet. Unless possibly racing in the desert, you will probably be wet throughout most races between water, sweat, pouring water over head, sponges, etc. The suit should feel tight
(though not agonizingly so
) and maybe a bit "indecent" when dry, and will look tight when wet, but you shouldn't be noticing any constriction of movement or breathing then.