What is this feeling?

Three years ago I was 18 years-old ending my freshmen year at Brigham Young University-Idaho ¬†and getting ready to head back home to New York City and get ready for my 2- year mission. Its crazy how fast time flies, but something I find crazier is having to continue something. I graduated high school 4 years ago and feeling the ending of that journey was something interesting knowing I was not coming back. The same feeling I felt when I was leaving for 2 years. Through out that school year I knew that it was going to be my first and last year for a while. Being shipped off to Paraguay for two years school and people from my past became distant. While being on my mission I was accepted into Brigham Young University in Provo, UT. Thats when I began to realize the my door in Idaho had closed and something new would start when I was going back to school. Now this is the first time in about 4 years where I am not ending anything. I am going to continue my education here at BYU for the next 2-3 years. I am filled with anxiety and confusion and stress. What do I do? I haven’t even been accepted into my program yet, meaning I don’t even know what I am studying. Things are moving so fast and I am saying goodbye to people who were in the same position as I was 3 years ago. But at the same time I look back and I am proud of where I have come. This is my first time continuing, but this is also the first time my life has begun to settle in. I am a lot more independent, 21 years old, living in an apartment I pay for, working as a social media marketer/advertising intern, having friends and just feeling closer to God. I guess I just have to continue to grow and learn about what real life is. What it really is to just continue on with something.