You're asking too much too fast. I don't barrel race but I did take lessons on an ex barrel racer when I was 12. Learned to sit pretty on him but he was never go go go go go unless you asked him to.
She's young and you're asking for speed so early that she thinks that's what she's expected to do, instead of relax and only get speedy when asked.
That's why it's so important to always start calm and return to calm. There has got to be more to do with her than run barrels and get her hyped up.
Go back and spend more time on the walk once she is nice and relaxed (throw some lateral work in there, circles, figures, walk behind some cattle if you can not running after them or anything.
Once she's CALM, then you can ask for a trot and do the same thing until she settles down. Then once she's good on that, do some trot to canter transitions go from relaxed trot to canter for a few strides then back to trot and don't canter again till she relaxes in her trot.
Yes it's a pain in the backside but she's green and you're teaching her she has to just run like the cheetahs instead of control her speed and her anxiety level.