These things can be learned and gotten used to.
How many courses are you taking? What's your schedule like? If nothing else, expect to do a lot more studying after classes than in high school.
There are a lot of things you can do to help make this easier. For example, just as you have a course schedule, you can make a study schedule and work out how much time you'll need, and specifically when, to get all of your homework and studying done. Read and reread your textbook. Not only should you review your book and class notes after every lesson, but you should also read ahead by at least one lesson so that you'll know what to expect when the teacher discusses it, and it won't all be new to you. Otherwise, without knowledge of what's coming up next, each class will be something entirely new, and it will be harder to "make the pieces fit" as you assimilate all the new information.
