Sara,
You are *almost* going through what i've been going through myself!!!! Have you been reading my posts in my BF thread?? I have had to express on one side while the nipple healed remember? And I've had to give bottles (EBM & Formula) to DD since she was only 2.5wks old, i didnt have a choice she had to have them as she was losing weight and not gaining and not taking from the breast each time therefore my supply dropped etc etc (vicious cycle it became).... although Grace seems to be sucking fine, Ava was a lazy feeder which effected my milk supply so i had to build it up again.

Anyway, don't feel bad about expressing and giving it to her in a bottle but iykwim its upsetting I cried the first time I gave her a bottle, i cried the first time i gave her a dummy and i cried the first time i gave her formula!!!!!!!! This mothering is HARD WORK but you can do it.... I'm doing it so i know you can.... keep persisting it gets EASIER XXXXXXX
I always thought i'd just give her Bfing and never have to worry about bottles or expressing etc.... how wrong i was!!
ps expressing shouldnt hurt.... as long as you have the right 'flange' to fit your nipple if its too tight it will damage it (or may) and may hurt so make sure its the right size for your nipple and you'll know when it pumps does it hurt? if its comfy and not sqeezing nipple too tight then you are fine.
I had the Medela Mini Electric but it wasnt for high usage AND it hurt my nipple so i had to end up getting medela Swing (for every day use) from my LC. its great!!

Which pump did you get? Hopefully you won't be expressing for long.I've been doign it daily for 3 weeks but don't mind it now.....I thnk i'm going to keep doing it for a bit longer even if i don't have to.... i kinda don't mind it now just finding time is hard. However i had to do it for building my supply as well as healing my nipple.