Hi M.,
Sounds like you've gotten some great answers. I don't really have any advice to give you that is different from what you've already received. I know from experience that it can be frustrating, so I just want to encourage you, and let you know that you are doing a wonderful job!
My son is also three, and he has managed to get the "pee thing" down, but he still has a problem doing #2 in the potty. He has been wearing underwear for a while now, and doesn't mind going to the potty, but he won't go do #2 there. Tried everything I can think of. Got tired of washing out his underwear, so today I told him until he can do #2 in the potty, he doesn't get to wear underwear. Hope that works. If you happen to have any other suggestions, please let me know. Thanks!
Take care,
I.