Wow, you are fast, girl! Congratulations on your bike! I'm your height too, with about the same inseam (maybe .5" longer), and I have a 46 cm Aegis Swift with 650 wheels. I'm not riding it right now (long story) in favor of my 20" Bike Friday (even smaller wheels!) and mountain bike, but I never felt slower on 650c wheels at all, and they look much better proportioned with the small frame sizes. I really needed a 44 cm myself as the standover is just barely enough on my Aegis, but I got the frame on ebay for a song, so I compromised since the top tube length was fine; it's just a tallish bike. I never averaged as fast as you did (on your FIRST ride and when sick - wow!), but I was normally in the 16-18 mph range on my Swift and rode with most of the faster women in our club on the B-pace rides (just not the VERY fastest who rode with the fastest men on the A-pace rides), so I never felt at a disadvantage with the 650c wheels at all. And since I'm light, I only got about 2 flats in a couple of years of riding, so the tube issue just wasn't that big a deal. Just make sure to always carry one -- or two -- on every single ride since you may be the only one with 650c's on a group ride.

Enjoy your new bike -- and wheels!

Emily