Victoria's Secret Bathing Suit Question?

I'm trying to orders some bathing suits off of VS but i don't know what size to get. I've only gotten 1 suit from there before and it ended up being smaller than I planned. I'm a 32B bra size and a size 0-00 bottom so according to the chart I should be a S top and XS bottom. I'm 5'5", 115 lb and have NO butt. Should I get the size they're telling me to, or do they run small? Specifically the bottoms. Thanks.