You cannot fight against the ego and win, just as you cannot fight against the air - Eckhart Tolle
Boy Korbbit, as so many others here already said, I can surely relate to your position on life. It happened for me in roughly the same way, a constant ache in my heart for something lacking, something just not right about life on Earth as it was being presented to me. Death was a problem that no one seemed interested in grappling with until it was unavoidable, but for me life was impossible to live so long as death cast its shadow over it. So, from a very early age, I tackled the biggest philosophical problem of all: if death is the great equalizer, what meaning can anything I do in my life possibly have?
I'd see people running around pursuing relationships and money, trying to make it in life and I was sort of on the sidelines, watching life as it seemed to pass me by. Once I could break the shackles of western Christianity had placed on me, I began to pursue this idea of enlightenment. The concept seemed to fit nicely into what I was looking for: that there was an answer to life's many woes that a human can figure out somehow. This began a long, hard road that did end up having a happy ending (I get life now and am at peace with it). However, entheogens were only the final key I needed to pick the lock on life's mystery, I had already had a measure of understanding before I went into it as a spiritual pursuit.
I've been doing some study of Hermeticism lately. Briefly stated, it's a very old gnostic philosophy that was highly regarded back in the day (until Christianity all but wiped it out). One of the key concepts I've come to understand in Hermetic thinking is what's called the negrado, or the blackening. In old alchemical thought the negrado was the lead that was to be turned into gold, but in hermetic thought the negrado is a prerequisite to attaining a deeper understanding of the universe. It's a process whereby the human soul burns out all of the shit that can be considered wrong in life. It's the decay of a lifelong friendship with the realization that the friendship no longer serves the highest function of the soul. It's the breakup of a marriage because the two parties are not really truly in love with each other and have been just going through the motions. It's losing a job or a career that was taking you in the opposite direction of the spiritual path. Basically, the negrado is a process of suffering that opens the door to enlightenment.
I'll use an illustration, are you familiar with the japanese anime Dragonball Z? Hopefully you are because the way the character named Vegeta in that show attains the super saiyan state is similar to this concept I'm talking about. For the entire anime this character Vegeta is questing after this mythical and powerful state called a super saiyan. In many instances, he falsely claims he has attained the state of super saiyan only to get utterly pummeled into submission by a more powerful foe. After his rival Kakarot and his son Trunks attain the super saiyan state and he still cannot, he nearly goes mad in his pursuit of it. He leaves planet Earth to train in the greater universe, and no matter how much he tried he could not attain the super saiyan state. Then, one day in exhaustion, he is on a planet that is surely about to be destroyed due to a meteor shower. Having no energy left, Vegeta finally comes to a place where he didn't care anymore. He didn't care if he ever became a super saiyan, he didn't care if he was better than his rival Kakarot, he didn't even care if he lived or died. And it was there, in that moment of having nothing that it happened: he transformed!
Enlightenment is sort of like that. You will never 'attain' it so long as your looking for it, and yet at the same time it requires some effort in seeking on your part doesn't it? It's a complete paradox, but it's not without it's own way of working itself out. There is a school of buddhism called Shingon Buddhism (probably not spelled correctly). It probably has the best understanding of how a soul attains enlightenment. In the Shingon school all one needs to do is call upon the name of the buddha once, only once, in true sincerity and eventually, no matter how many reincarnations it takes, the seeker will attain enlightenment. That's sort of all you need to do. Make up your mind that that is the goal, and your life will take you down that path probably in ways you didn't expect. So, see, you say you have issues with depression and the person you are but you seem to already have set your esoteric eyes on enlightenment as a worthy pursuit. That path is not a rosy path, and every person who truly wishes to go down it will be met with their own challenges and blackening-type experience.
Think of it sort of like how Christ says that to enter the kingdom of heaven you must be born again. It's like that, and what comes before rebirth is, sadly, the death of the old way of life. This is painful, this HURTS! But it's necessary to break us out of our old habits and shitty way of looking at things. If the things in your life were already what they needed to be, you wouldn't need enlightenment would you?
Entheogens are tools and they seem to always give you exactly what you need when you need it. If you had a really bad experience, you probably needed to have it. I absolutely understand how horrifying a bad trip is, I've been there myself, but even the worst trip I ever had, upon reflection, turned out to be a road mark on the path to enlightenment. Sometimes we have false things so embedded in our psyche, even unknowingly, that getting us to see the truth can sometimes be excruciating. My worst trip, I had to come face to face with a voice screaming at me how unworthy I was of the hyperspace realm, how that was a holy place and I was sinful. When I finally had the courage to look at what was happening, to see that this was my EGO trying to convince me to stay with it, in it, that voice stopped and I've never had an issue with feeling worthy ever again. In a vision, I saw the ego curl up into the fetal position and whisper, like an infant 'don't leave me... don't leave me... i don't want to die...', and from where I was I couldn't understand what the damn thing was getting so worked up about!
This is a hard path my friend, but the rewards are worth it even if the process is slow. Sadly, enlightenment isn't something that one just gets overnight and that's the end of it. No, rather, enlightenment is like that path less travelled in Christian philosophy. It's a path that one takes in life, with all the twists and bends that come with it.
Keep at it, and whether a month, a year, ten years, or several lifetimes, you'll get it friend. You'll get it.