Ugggghhhh.... Girl, I know what you are talking about. My daughter was like that. She expressed an interest in the potty at about 18 months. We didn't make any big deal over it but when she was about to turn 3 I freaked & started really trying to potty train her. Nothing worked! We did charts, where I drew 5 blocks and each successful potty trip = 1 sticker; 5 stickers = McDonald's playground trip. SHE DID NOT CARE (but try it - yours may)!
What really worked with us is that I played the "Stupid Game". Whenever I had to go to the bathroom, I would go to her and say, "Hey, help me out - I feel something down here in the bottom of my belly and it feels like it needs to come out! What is it? What do I do??" I played really dumb and confused so that she would HAVE to show me where the potty was and take me through every step! (Hey, at this point I had thrown away ALL pride and self-respect!) In a couple of weeks it worked for peepee. Now, poopoo was another story - again she was stubborn and kept doing it in her pants...UGH. I started back to being stupid, even though it was harder because obviously we pee more than we poop! But again, in a couple of weeks she was telling me that she had to poop. Ever since then she has never had a #2 accident (she's had a lot of #1 accidents lately b/c she doesn't want to stop what she's doing and go to the bathroom).
Just be as patient as possible. I *know* that is hard to do, especially if you have another baby on the way and don't want to have 2 in diapers. If you have someone who can give you a break from it every once in a while, USE THEM! They will be able to be more laid-back with her and it may help for her to hear another point of view.