It might be worth getting properly diagnosed…then you could get accomodations at school such as extended time, a quiet room, and scrap paper for exams/tests/quizzes.
Your college may be able to do the evaluation for you…e.g. at Rutgers
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Psycho-educational Evaluations
The clinic in Rutgers Graduate School of Applied and Professional Psychology has personnel certified to administer the test batteries used in diagnosing learning disabilities. ODS determines students’ eligibility for this service. You are welcome to refer to us undiagnosed students exhibiting some of the signs listed above."
Also you have to evaluate if business is the right major for you. Obviously at work you could use a calculator/spread sheet, but to be able to estimate and see if a number seems like a resonable value are skill you will need. Some business majors may need advanced math (e.g., economics)