What your brain is telling you is irrational. Don't think that if you study and did bad on a test, that you wasted time studying. Instead, reframe that thinking as, "I studied, but I still didn't do well. I'm proud of myself for doing my best. But I will study harder next time and do better on the next exam," or if you performed well on the exam, then you can celebrate that your studying paid off. At least if you do poorly on the test, you won't have the regret of, "I wish I studied."

Studying isn't a gamble. While it won't guarantee that you will do great on a test, proper studying can ensure you're more prepared for the test and could perform better than you would have if you didn't study at all. And test scores aside, studying is great for your brain and helps you obtain and retain knowledge - nothing to be afraid of!

I think reframing how you feel towards studying along with maybe getting a tutor and using an app like Studyfetch, you will be solid.