Cows milk is hard to digest. I wouldn't rush to give it. You can start giving her water with meals though, assuming that she is a) eating meals and b) drinking out of a cup.
I would drop one nurse at a time, giving at least 3 days for your body to adjust. I don't know how many times per day she's nursing now. I would drop the middle of the day ones first, then the morning one, then the before bed one.
Finally, I don't know how you are with engorgement, but I had it terribly whenever I dropped a feed. You can pump a little for relief, just be sure not to empty your breast, which you probably already know, just wanted to remind you.
Congrats on making it this far with the nursing. You did a great job and you should feel proud of yourself. I think it's totally reasonable to want your body back at this point.