Feeling depressed about time. Im only 19 years old. Any advice?

This happens to a lot of people, if not everyone. The important thing to focus on isn't the past, and what you may or may have not done. You must live for the here and now (and your future, which is why your college life is important), instead of focusing on the past, which is something you cannot change. The present will be the past eventually, and if you worry about things you cannot change, then this time in your life (at age 19), when your 20 will be yet another time you regret because you've wasted it thinking about past regrets. Things in the past cannot be changed, this is a truth we must all face. Yet, on the other hand things in the future can - this is why you must remember that not everything you are going through right now is permanent, thus a reason for you to live now, and not back in highschool or at any other point in time. Take one day at a time, and remember the good ones.