Definitely keep encouraging her to sit. But don't let her flush - that privilege belongs to people who wee (I tell this to Toddlers every day )

At CC, I get kids to stay on the toilet for as long as it takes to sing Incy Wincy Spider. I also a little bit hope that the "down came the rain" bit might have an effect!

Make sure it's a no-pressure environment. And don't expect too much too soon - she might still be months off. But sounds liek you're doing all the right things so far! Good luck.