I have recently found that preemie pajama's work great for little girls/boys!! I have bought baby clothes for my bigger girl (around 9lbs) Joli before (usually 0-3 month t-shirts worked great), but I tried newborn dresses for Somi and they are usually two wide at the bottom and look kinda like a moo moo. BUT I found some adorable preemie pajamas at Marshal's or Ross or somewhere like that and HAD to try them. I cut the feet off and a "pee hole" and they work great and seem to keep her warm and cozy!!
The ones with the zipper that I have, have a little triangle sewn area near her tail that was PERFECT to cut out for her pee hole. And I got some really cute ones off of ebay that ended up being a little smaller and they had buttons that go down both legs, and just leaving some of the buttons on the legs open the private areas were open. They also have little panda's on the feet, so I only cut a slit in the seeming for her legs instead of cutting the feet off.
I hope you get lots of cute (and practical) clothes to keep your furbaby warm!