Thank you for writing. The first thing to do is to get a complete medical checkup. Sometimes the emotional ups and downs that you are reporting have a physical cause. Make sure you check it out before you decide that this is all in your head and start worrying about a mental health diagnosis.
Having said that, I do have another idea. Sometimes our inner self is wiser than we give it credit for. It just may be that your emotionality is a way you are telling yourself that you are simply not interested in college at this time. I want you to know you’re not alone in this. Many recent high school grads have no idea what they want to study or why they are headed to college. Everyone they knew just kind of assumed that of course they were going and they went with what felt like an inevitability. Often these are the kids who drop out. If they do complete the four years, they often aren’t happy with the major or the career they ended up with.
I think you should take a step off the conveyor belt that is taking you to college and really think about what you want to do. It’s not a crime to go your own way. It’s only wise to take time out to figure yourself out. There are progams called “Gap Year” that are intended for teens just like you. Search the web and you’ll see all kinds of interesting ways to make a contribution in the world and to expand your own horizons. I wrote a couple of articles for Psych Central that address this issue because I was getting many letters like yours. Click the links to take a look.
You are your own person. You are not your sister. You are not your cousin. Taking more time before choosing a path toward your future is only smart. College costs a great deal of money and time. You want to be sure that it is necessary and that you are motivated to do the work before you pack your bags to go.
I wish you well.