I don't know who/what I am? No spiritual connection / Confused
I'm going to give you practical advice as I'm turning 60 this yr and I could have written your letter when your age.
-learn to discipline your mind and your life. Discipline is everything.
The reality is you are in this world and most people are not like you and that is a fact.
Thoughts that are not beneficial to you should be discarded. If you are in your head too much you need to shift to doing things. Accomplish that which moves your Life forward, whether that is organizing a bookshelf or creating a musical masterpiece. Keep active, force yourself to keep moving forward.
-support people in your Life will make a huge difference, continually seek souls like yourself.
-find a release, a passion (or 2) and continually express yourself through this and do not pay attention to what others say about this avenue, it is for you.
-accomplish things, whether small or big. It will make you feel good about yourself.
-diet can influence. Things like coffee or Sugar may be adding to those deep moods.
-get informed about HSP (highly sensitive people). They have shorter iliads in the insula in the brain causing hyper/overload of information. Vids by Elaine Aron are very good.
-homeopathy can help you tremendously!!!
I'm also pretty sure you had severe trauma in your past whether you know about it or not.
Find some words to live by so when you have your dark moments you can grab onto these and have a way to direct your Life back into the direction you truly wish to go.