A pit for your first puppy is a brave move. I love pitbulls, but they are a breed that can be a bit more challenging to train. The key with a crate is to get one that fits her. Make sure that she has enough room to stand up and turn around, but no more than that. The idea is that dogs don't want to "go" in their bed, so it will encourage her to learn to hold it.
Also, if she is 2 1/2 months, she may need to go potty more often than that. They say that every 2 hours a puppy that age should go out, at least. But from my personal experience, when both of my dogs were that young (i shouldn't say "when", one of them still is that young!) they needed to go out at least every half hour. Sometimes more than that.
Also, I don't know if you are or not.. but a feeding schedule should help with the erratic pooping.
