How to potty train girls?

Hi! I have a 3 year old girl and I am trying to potty train but she will not under any circumstances catch on. I have tried a childs potty and our toilet. Tried giving rewards. Dancing and praising her. Having her wear underwear to feel like a big kid. Nothing seems to be clicking. She will pee if I catch it in time but she has no desire to tell me she has to go she will just go in her pants. I know every child has thier pace an I have been very patient and understanding to her maybe just not being ready but she starts preschool next year and a requirement of our kids school (i have 3 girls total) is they are potty trained. My other kids caught on quickly so I am at a loss on any other ideas than what I have tried. Any advice would be appreciated. Thank you in advance