I don't want to sound like a know it all... but...
The cause of your depression is your sexual practices. The "million dollar" spot you are talking about must never be pressed while you have a n erection, it will force micro-fissures in your ejaculation duct and completely destroy your libido in the long term.
You might be able to remain hard for a long time and eshaust partners, but thats not libido. Libido is when the penis bioelectricity creates a feeling of "vibration" in the spine.
Not only this is breaking your tubulures, you are also detroying your testosterone hormonal axis, you must produce way too much adrenaline-cortisol. Your dopamine must be extreemly low, your serotonin unable to buffer the up and downs.
And most sad of all, you must not attract many ladies in a purely physical way ; but don't loose hope, anyone can heal and they have in the past.
If you start by regulating that ejaculation frequency, you will see immediate improvement, you see its not about the nutritive value of sperm, thats ridiculous mythos made by people with tight prostates, who cannot make a godess climb to the 7th sky. It's really sad I know 90% of the so called gurus tell you must not waste the sperm, scientifically... this is totally ridiculous. It's the regulation and emptying the gonads not fully , maybe 2 thirds, which is important, it signals your body that your cycle is understood and it starts to heal.
Sorry there is no other magic way to heal, when you penis is full of libido ALL THE TIME, you will be so hot you will bet dozens of smile from ladies everyday, but since you wont be so edgy on adrenaline, you wwill be able to control yourself so well that they're even going to be impressed at what a man you are.
You're going to have to stop smoking mostly as well, your liver is obviously sick. Especially smoking WITH masturbation... sorry to sound so alarming , but I have studied endocrynology for 5 years and treated people for this kind of problem for 3 years, couples too. This is my actual job, and there is no ambiguity in this. If you choose to smoke, you must not masturbate, anytime you do hormone altering drugs, you must not have sex, or you're going to sink even lower in the depression. Not only you wont enjoy the cigarettes like you can, you will live generally less. By what you say I feel you are meaning to say you prefer to live intensely than for a long time, thats why you keep cigarettes and the enjoyable state of mind , cool and stimulated... but that tought is going to catch up behind you.
Don't turn yourself into a farce, you're still young it will be easy to heal ! I healed from a similar condition myself, and helped many people. You will need kava, and magnesium and fish (or golden algae) oil, and other stuff...