Are the math questions slowing you down? There are so many useful tricks in math that can save you time. If you can go from two minutes per math question to under one minute per math question (and this can be done VERY easily with the right approach), then you can save enough time to get into the 50s in terms of questions completed, hopefully all 59. There are ways to get pH in 20 seconds or less, get buoyant force in 15 seconds, complex circuits in 20 seconds, lenses and mirrors with tricky numbers in 10 seconds. You need to master those and many others if you want to become faster.
In addition to math, there is a sort of flowchart approach you need to develop, as it will save time you may now be wasting with random thoughts. Write systematic answer solutions for various questions that focus on the minimal fundamentals needed for the question. As you write them, think it out loud. Become more systematic and you'll save time.
The science sections are the easiest areas to improve given your background with the material. Good luck!!!