Well, you made it this far. I don't think you ever thought that you would end up where you are at this moment. Sure, it's not what you had planned but it is where your supposed to end up. Always remember to keep your head up. You know how the saying goes, "when the going gets tough the tough get going". You may not have your life figured out and you might think it's in shambles but I can assure you that it's not the end of the world. Sometimes in order to be found you need to be lost first. You just have to keep doing what makes you happy. Forget what others have to say about your choices, it's your life to live anyway.
Maybe that boy you thought you were going to marry broke your heart or you broke his, or you didn't do as well on that job interview as you wanted too. Life goes on. Relax, eventually you will figure everything out. I know it's hard to see now and even harder to believe. It probably feels as though your world is collapsing and as it turns out everything you thought you knew is actually just all one big lie. As Andy Biersack once said "Every sixty seconds you spend upset is one moment of happiness you will never get back". Eventually life will work it's self out, maybe not today, maybe not tomorrow but it will.
In the meantime enjoy the little things in life because one day you will look back and realize they were the big things. Collect moments, not things. Most importantly, do what makes you happy, no happiness won't pay the bills but it will complete you. Laugh often. Worry less. If you shed a tear make sure that it is for the right reason and not for the wrong one. If you must control the situation, control the things you can take of; whether or not you go to bed happy or sad, spending time with your family/friends, laughing or worrying. As an unknown author once said "You may not always end up where you thought you were going, but you will always end up where you are meant to be". It might not all be figured out yet but eventually it will be.
I hope you don't stress over the little things but learn to let go of them. I hope that for every door that closes, you look for a new one to open. I hope that you learn that having all A's isn't everything. I hope you live in the moment of every day life and try not imagine worse case scenarios. I hope you look for the good in every situation. I hope that you choose the choice that is right for you. I hope that you realize you may not have your life together right now but that doesn't mean you never will.