What Am I Missing?!?

In the process of potty training, both of my boys learned how to pee in the toilet long before learning to poo... (yes, we are encroaching on that topic). It then took time to teach them about the #2 part of toilet etiquette.

Ellie, however, has been completely different in her training techniques. She figured out how to pee on the potty, but not how to tell me when she needs to go. The effect is simply that when I insist that she sit on the potty, she indeed releases the built-up liquid. But if I am not preemptive, she will have a wet pull-up.

BUT -- She knows when she has to go #2. She will tell us when she needs to, and she hasn't had that kind of accident in over 2 weeks!

I don't know what I'm missing... How do I finish the potty training process so that she will tell me when she needs to go? Don't get me wrong, I LOVE that I haven't had to deal with poopy diapers. But I would also really love it if I didn't have to buy pull-ups at all anymore. Help!?!