Thank you for writing. I sympathize. Launching into adult life can be very, very scary. You are certainly not alone in this.
I’m concerned that your worries are keeping you awake at night. It may be that you are now caught in a cycle of sleep disorder and anxiety. Your worries keep you from getting good restorative sleep and your restless sleep is causing you to be more anxious — which is keeping you up at night.
Help starts with getting some good sleep. If you haven’t already, establish a sleep routine. Get off all screens an hour before bedtime. Allow yourself at least 8 hours for sleep. Do calming things before bed. If you find that you are making lists or obsessing about something when you are supposed to be sleeping, write it down in a notebook you keep next to your bed. Then remind yourself there is nothing you can do about it at night, but you will deal with whatever is in that notebook the next day.
As for the worries: As you have already discovered, if you don’t deal with the issues directly, they don’t go away. I wonder if there is a mental health service or support group for students at your school. You need some practical advice about how to make yourself marketable as well as some support to develop a stronger self-esteem. Please take advantage of whatever help is available. You are smart enough to be at university. You are also smart enough to solve life’s problems once you have some direction.
I wish you well.