It sounds like she's manipulating you. You are the parent. It's your responsibility to make sure she is at school on time. Make it happen.
So, how do you do that? Definitely an earlier bedtime, so she's well rested. Move it back 15 minutes every few days. My kids start the bedtime routine between 6:30 and 7, with being in bed by 7 to 7:30. Asleep long before 8.
Our routine looks something like this for both our kindy, and our 4th grader. When homework is done, I check it, and then it goes back in the homework folder, which goes in the backpack, which hangs by the door. At that time, I get lunch box (4th) and water bottles, and empty them. They then go change out of school clothes and lay out what they are going to wear the next day, down to socks and underwear. Sometimes their beds didn't get made in the morning, so they do that at this time, so the clothes don't get lost in the messy bed. Shoes are kept by the door in a basket under their backpack, so they don't have to lay those out.
Our kindy is really distractable, so at bedtime, he has a laminated strip of a little boy that has a picture of jammies, a toothbrush, and a medicine bottle. We hand this to him, and ask him to go get ready for bed. He brings us the strip back when he is done, and we confirm he has done everything. (We actually help with the medicine, before anyone goes berserk on that comment.)
In the morning, we do the same thing. He eats breakfast. We tell him how long he has to eat, and set the timer for him, so he can see how he's doing. When he's done, we hand him the picture of the little boy again. Right now it has a shirt, pants, socks, and underwear, and toothbrush, a hair brush, and a medicine bottle on it. We ask him to go get ready with this, and bring it back when he's done. We're transitioning to just a picture of a little boy dressed, but not yet. This has helped a lot.
The other thing we've recently instituted, and has helped both our boys, is we have 20 minutes of quiet music playing for breakfast. Breakfast is over when it is done. We use the same music every morning, so they know when the end is in sight. While getting dressed, we have 10 minutes of music, and another 10 for hair and teeth. We end with 10 minutes for assembling everything to get out the door. Really that just involves snack, water bottle, lunch box, and coat. 50 minutes total, which is really longer than any of them need, but it helps everyone keep on schedule, and since they are up on their own earlier than this, we have the spare time. Our mornings are much calmer and quieter. Even my 3 year old can get out the door on time by herself with this. In fact, yesterday, my husband was off, and never heard the kids getting ready other than when my daughter came into our room to do her hair. He slept in the same hall the entire time! Yay, kids!
And yes, as others have said, it's not the end of the world if their hair isn't done, or whatever. Our kids have gone without homework, because they couldn't find it, their hair undone, their teeth unbrushed, dirty underwear (with a little stigma added :) ), etc. They only do it once or twice. My kindy actually went without the correct uniform one day after arguments, which meant he didn't get to wear his regular clothes on the day of choice. Kids get it. Even a clueless 5 yo.
The calmer you can be, and the more physical helps you have, the easier it will be. The more worked up you are, the worse she will be. I know it's not easy, but you really do set the tone for the house. Hang in there, and try several different ideas. You'll find something that works. GL! :)