At least you appear confident to others. That's a skill in and of itself. It's something I struggle with personally. Nobody wants an uncertain nurse providing care.
As far as easing the transition, there's not a whole lot you can do. It's one of those things that just requires time and experience. I'm a 3rd semester student and I still get nervous and I still make my fair share of silly mistakes. My best advice is to follow safety procedures (like you did with checking the insulin with another nurse). Those procedures are in place to help prevent those silly mistakes, even after you've gained some experience. Know those safety precautions front and back.
Also, be prepared for clinical. Make sure you know your meds, including related issues or labs. It's important to know how they work and what that means for your patient. Can this med cause bleeding? Do you have parameters to hold it? Are there labs that correlate with the med? That's what preplanning is all about.
You'll be starting off slow in 1st semester. They won't just throw you in there. First semester is mainly about learning how to properly assess your patient, which can be just as difficult as preparing medicines.
I'm sure you'll do great. Give it your best effort. Good luck!!!