I buy 10s now and I *still* expect people to scoff and kick me out of the regular petites section. So sad.
I don't know where you live or what your body shape is, but I'm an hourglass, and when I first downsized from plus sizes the place that worked best for me was, believe it or not, Wal-Mart. Their George brand makes decent pants that hit at just the right spot on the waist (at least for me) and didn't sag in the butt like pants often do. Also they aren't super-expensive, which is a bonus when you're going through sizes like crazy.
Of course, I hem a lot of regular length pants these days, because I only buy on clearance/second hand while I'm losing, and there aren't many petites in the clearance sales or second hand shops. But you might try Wal-Mart. Old Navy has a few styles that worked pretty well during that transition period, too.
If neither of those suggestions work for you, you might try adapting to skirts for awhile. They are much more forgiving of our weird body changes.
Good luck! And welcome to the 'regular' section.