OK just wanted to send my hugs over to you! my girls are 3 1/2 (i have identical twin girls) and they still aren't potty trained. we have also tried everything from the rewards chart, the sticker chart. they just don't do it and they know what to do. They tell us every day, " babies wear diapers, big girls wear underwear!" but then when we say but are you a baby because you were diapers, they will answer, "no, I am a big girl!" they will tell you until they are blue in the face, peepee and poops go in the potty. but if you ask them why they peed or pooped in their diapers, they will only repeat back to you, "peepee and poops go in the potty!"
they just started preschool again (we just moved states) so we are hoping that they see the other kids "doing it" it will ease them into it. just keep being consistant and it should one day just pop and work! that is what i am hoping for soon!