OK, let’s try this approach:
Next test, give up on the idea of getting a perfect score. Instead, go in with the mindset that you’ll maximize partial credit. Tackle the problems you know you can get through quickly first. Next, the ones you know you can start. When you get stuck on those problems, don’t sweat the finish. Instead, write a narrative. (“I know I should factor this, then set each factor equal to zero, and eliminate any negative roots, but I’m getting stuck on the factoring.”) Once you’ve explained your way through each problem, leaving no blanks, go back and really tackle the ones you’re stuck on.
For some kids, simply letting go of the idea that they should finish every problem is the key. They relax and show just what they do know.
Maybe run that whole strategy by your teacher ahead of time, just to see whether she would give any partial credit for a narrative. I know I would, and have.
If she says no, then here’s what you do: totally fake the parts you’re stuck on, and finish the problem. Let’s say you can’t remember quadratic formula. You write it as best you can, get some sort of an answer, and FINISH the problem. Yep, you’ll lose points for missing the formula. But you’ll get those points at the end of the problem.