Carrie, I completely relate to your frustration. I was maid of honour for my best friend this past summer, and trust when i say I was ready to kill her after a year of all sorts of crap (including her bitching me out at her bridal shower after she showed up 2hrs late). There were several times where I wanted to confront her about some things (including expecting me to spend a lot on wedding related outfits that i could not afford). I talked to her about the smaller stuff, but waited with the bigger things. I ended up not talking to her about these things until a few weeks after the wedding. I didn't want to upset her and add to her stress. Also, i didn't want us to fight before her wedding. She's like a sister to me. Part of me regrets not talking to her before the wedding, because i wasn't able to enjoy the festivities as much because i was annoyed. But she had a great day, and was thrilled that i was there by her side. In retrospect, I'm glad I let things wait. We had a long conversation after the honeymoon in which i told her how i was feeling. She was very receptive, and apologized and even pitched in 200$ to cover some of my wedding expenses. I'm not sure what the right decision will be for you, but whatever happens just remember that the brides in genera; get VERY self involved and become totally oblivious to others probs - not because they don't care, but because they've got so much on their plate and are pretty overwhelmed.
Please, keep venting to us and to your other friends. It'll help you feel better. Good Luck!