Dear V.:
I did a combination of things to get my daughter out the door when she was younger. First off, we organized all school supplies and clothes were picked out the evening before. Get up the same time every day, earlier if you need more time, later if you don't.
I also found a combination of breaking up the morning into smaller pieces and rewards worked well. Instead of saying, "Time to get up. We have thirty minutes to get dressed, eat and brush teeth," it was "Time to get up. You have 10 minutes to get dressed." Then I'd say, "Sit down to breakfast. You have 15 minutes to eat," et cetera.
What also worked for me was if my daughter was running ahead and had absolutely everything done and it was too early yet to go to school, she would get to watch a cartoon. The TV was only turned on AFTER everything was done, not skipping any steps in our routine. Also, she only got to watch the program until it was time to go, finished program or not.
To start with I had to get up earlier to get myself ready to go and pretty much micromanage her to get her on track. Once she got used to the routine, and with the reward of a cartoon if she was done early, our mornings were pretty good.
I would also tell my daughter what my mother told me: If you're running late and cranky in the morning that means you're not rested enough. That meant going to bed earlier and getting up earlier. It really works!
It will take some work on your part, but getting the morning routine under control is really important. It's ruining your day AND your daughter's. Hang in there. It will get better with some work.
L. F., mom of a 14-year-old daughter
P.S. After ready the other posts I had to agree with a couple that said take her to school as is when it's time to go. My daughter has brushed her teeth in the car, finished breakfast or finished dressing in the car a few times. It was a learning experience. She is an extremely responsible 14-year-old and has NEVER been tardy to school!!