I am also an 18-year-old, and I am proud of you for coming here and post your message. Welcome to HW!
If you want, you could write a bit more about the things that make you feel depressed. I encourage you to post it here, as other members might be able to help, but writing for yourself is also a great help in exploring your depression.
The anxiety you mention is quite common, I know a lot of guys and girls (including me) that have or had that. A question though, do you still feel very anxious while you are hanging out? For me, it is the thought of going to that is the hardest, but once I got there things are actually quite relaxing.
But there is a lot you can do about it. Have you told any of your friends already? They can be such a support during a depression. It is awfully scary, but the relief and reward after you have told them is worth the effort.
I wish you all the best, and please keep talking to us!
Acceptance is the key
The World is but a reflection. Smile, and it will smile back.
Try to keep smiling! :)