Im so insecure in college?

Well I'm glad you mentioned how proud of how far you have come because that is the very first thing to keep in mind here. It isn't easy for someone to come to a foreign country and you can't expect to just fit right in. The fact that you've made it this far is an incredible feat. Now you need to go and speak privately to your counselors and teachers, sharing your concerns. It won't be easy, especially going to the one who kept pointing out your errors. But you need to express your feelings and get their advice. Wishing you the best for your future.