We tried several different bottle/nipples, too, when I was giong back to work (DD was 2.5 mo). We found Medela slow nipples to be too fast. DD was choking a lot. DD didn't care too much about the bottle, though she preferred wide bottles. We ended up settling on Gerber NUK bottles. Her favorite nipple was Gerber NUK orthodontic slow flow nipples. Also my dentist sister recommended the orthodontic nipple for being better for baby's mouth development. You can buy these separately for a few bucks and put in your favorite bottle. They come in both narrow and wide bottle fit.
Another plus for using the Gerber NUK bottles is that they sell a sippy spout that you can put on instead of the nipple. ($2 each at www.gerber.com
) This way, you get a really long use out of your bottles and save tons of money when baby is ready for sippy cups ($5-20 per sippy cup!). These are the BEST sippy cups (we tried over 12 different kinds) for us (DD is currently 13 mo)!!!!!!!!!!
Good luck returning to work! First 1-2 weeks are very tough but you will quickly settle into a routine!!