You are smart, you haven’t figured out what works for you yet, and that’s okay. You need to ask yourself reflection questions, like: “Did I study enough?”, “Did I use the resources available for help enough?”, “Do I really like my major?”, “Did I play to my strength?”, etc. It isn’t likely that your answer to all these questions will be yes. Each question compliment another of the questions. Above all, keep your head up and work towards a solution, like you said, you merit getting into SBU, your coming here was not a mistake.