Is it possible to feel happiness or joy or excitement? Is it possible to feel anything other than deep regret and hopelessness and extreme pointlessness?
Perhaps I'm extraordinarily fortunate, but I often feel happiness, joy, and excitement. Once in a while I feel regret when there is a reason, but the occasions when I have ever felt hopelessness or pointlessness have been quite rare and very temporary. I don't believe it's normal to be in a constant state of despair. Perhaps you should consider speaking with a professional.
I think that post you wrote is a good first step. You spoke out. You put your emotions into words. I suggest you keep at it. Find someone to talk to. Someone you trust, or someone who might have a complete outsider view on what you're going through. Keep letting that steam out.
Sure the universe is chaotic and goes from the infinitely big to the infinitely small. The infinitely ugly to the infinitely beautiful. The infinitely cruel to the infinitely kind. Just look at it at your own human scale.
I think the future is a blank page. Nothing is written and decided in advance. Pay attention to what gives you regrets, what makes you loose your hopes. Find some allies, people who think and feel like you do and find out what's the next step you can take.
I'll echo those who recommend counseling. There are meds for depression (which certainly is described in your second sentence.) YES! It's possible...but you must do the work and you must be willing to feel confusion and pain while you're doing it. I wish you well!
I suggest you see a counselor. This is your LIFE, not a rehearsal.
An ebullient optimist, I experience joy, excitement and happiness every day.
As I wrote in my profile:
I find the wonder and joy in life. The infinite pleasure in the touch of a hand, the joy of tasting a juicy, ripe peach. Intense, playful, passionate and determined, I have fun every day.
I love hiking to alpine lakes surrounded by white glaciers and jagged mountain peaks. After dark, I look up and feel awed by the glowing Milky Way and billions of sparkling stars. We all need more low-level ecstasy in our lives.