I just wash the things in the delicate cyle of my front loader with the same detergent I get for lingerie; they wear like iron, they don't pill or snag, and they hold their shape beautifully. After nearly 2 years of very hard wear, they still look like new: this includes coaching, skating, falling, getting up etc. They've outlasted everything we've had except for ... sigh ... the old BlueSkys skatewear line. I figure they're good value for the dollar given how long they last.
Watch for them on sale ... I've seen them on a bunch of different US skate sites at a discount - !
However, there is at least 2 different types: the ones that are made of the "novelty stretch fabric" aren't as warm or thick as the "classic sanded Poly Spandex Fabric"; there is now a new polar fleece type, we haven't had any like that. The ones you want, they are the classic fabric, and we've been very happy with them: because they're reversible, you can flip them to plain black and they "pass" as regular stretch pants instead of skating pants.
We bought the ladies large for my daughter: she's about your hip size, smaller waist, however, we had to go for that one because of the length of her leg - she's very very tall for a skater and long-legged. I will point out that they do fit very snug in the thigh and crotch area, but, not, fortunately as tight and - defining - as lululemon pants do (she wears a 6 or 8 in that brand.
I would contact them and ask for advice. We had a problem with a jacket for my little DD. The fabric didn't wear well ... I e-mailed them, they immediately replaced it at zero cost, and the new jacket has worn as well as the pants have. The customer service is fantastic.