K.H.
My daughter (now 5) potty trained at 2 1/2 but I let it happen in only a positive way-some kids don't train until 4. I'm not a big tv person but on a recommendation, I sat her in front of this video called "Once Upon a Potty" I let her sit on her little toilet while watching. It's magic, I swear. We had fun singing the potty song. I let her move the potty to different places for the first week. She loooved the video and she literally did it herself. I made a sticker chart and every time she even tried to go she got to put one on, then it changed to getting 3 stickers if something came out, then it turned into a sticker only if she went every time, etc. But the video and the song...so catchy and it worked (it's funny too-seems like its from the 70s)
As far as weaning...my other daughter now 17 months latches on but there's nothing in there anymore so I just keep saying, "You can try but its all gone," then I have a cup of milk or rice milk there for her to have.
Now after a week of that, she rarely tries. I don't know if you have a lot of milk left but I pumped one day and only a trickle came out so that made me realize she was only doing it habitually.
And, she's been trying to use the potty. I think the important thing is not to force it, just to have fun with it. Have your boys encourage her to be a big girl. Hope that helps! Everyone is different as I'm sure you know :)