I won't offer you any advice that your 10 year older, wiser self is unable to follow. Know that you are capable of doing everything in this letter.
First, you know those suspicions you have of what your future life will be like if you don't take action now? They turn out to be true.
Second, lighten up a bit when it comes to relationships. There isn't a "one" out there, but rather a one in a million. You will learn more from your mistakes than you will ever learn from staying inside your head.
Speaking of, you really need to quit complaining about your mom and start analyzing what YOU do to enable that crap.
Friendships are two way paths. Both people must give and take. Take a good, long look at your friendships and ask yourself which ones are symbiotic and which ones are parasitic. Be honest about which is which, even if you aren't ready to extricate them from your life just yet.
You know those crazy day dreams you have? You should listen to them. Instead as simply dismissing them as fantasy, realize they are clues pointing to the direction you must take. Never be afraid to acknowledge a daydream - there is no risk in that.
Most importantly. Taking ownership of your emotions. Good people have an odd way of accepting bad emotions as long as you admit to them and take responsibility for them.
Finally, if something is making you unhappy, why the hell are you doing it? That lesson applies to both big and small.
My 20 year old self in reply,