My 2.7 year old has had a pretty good start I think, did a couple of big wee's on the potty by the end of day 1. However, day 2 and 3 she sits on the potty for about 10 seconds, does a dribble, gets her praise and then gets up and thinks that's it! I know there's more to come as she's still holding herself when she stands up. Any ideas on how to get her to fully empty?