Sorry for the long post! But since money is involved, I want to give some backstory.
Our bride is far from a Zilla, mostly because she has a fantastic wedding planner who takes care of so many details that she hasn't had to lift a finger or give a second thought to any planning. Which is awesome, but she's remained naïve because of it.
This will also be the first wedding she's ever even attended. So that combined with the fact that all the details are taken care of for her, means that she assumes there's nothing left to do on her end, and she hasn't bothered to ask anyone or do any research to learn if there's an etiquette she should follow or if she has other responsibilities. (Not even a Pinterest board!! 
)
Since she isn't paying a dime herself and her pockets are pretty well padded, she told us that she would contribute $50 to each of our dresses (there are only three of us). When we found our dresses, she reiterated that she would contribute. But then she watched us as we wrote checks for the full amount and didn't say a word as though she had forgotten what she said 10 minutes earlier.
Now it's time for alterations. When the dresses arrived a couple weeks ago, she said, twice, that she would be covering the full cost of our alterations (there isn't much to be done). Well, we have our final measurement this week and she texted us "bring your checkbooks because they need payment up front."
And a few weeks ago she told us that she would be getting us all of our jewelry. But now she's only getting us the earrings, and we have to come up with the rest. And those earrings are her only gift to us. (Which is kind of a slap in the face since we've spent so much of our time, energy and money for her bachelorette party, helping her plan, attending things with her, supporting her in general, etc.)
Then she said that she'd take us for manis/pedis the day before, as her treat. Turns out she isn't paying for that, either. The groom's mom is. (Although this one doesn't really affect us, but I'm kind of appalled at the way she's backed out of paying for anything).
If she hadn't promised all of those things, it would have been fine as we could have budgeted accordingly. But because she pulled out of her promises, we've each had to scramble for an additional ~$150, which she is more than able to afford. Personally, I took all that money I thought I was getting a break from and threw it into her bachelorette party.
I'm pissed, but I'm not going to say anything as long as I'm the only one feeling like that. However, the other bridesmaids have dropped hints suggesting they're not cool with what the bride has done. So I was wondering, if both of the other girls come to me directly voicing concerns, at that point would it be appropriate for me (MOH) to speak to the bride (after the wedding)?
I feel like what's done is done, and it would be super awkward if she reimbursed us, and out of line for me to ask in the first place. But at the same time I want her to be made aware of her behavior and to see how much we're doing and spending for her. If it is ok for me to bring it up with her, what's a tactful way to do it?