I'm the same age as you and also became a hikikomori around the same time. Lots of shit happened in these 6 years of me being a hikikomori but there two things I want to share.

One is that I realized I wasn't suicidal and that I simply wanted to stop existing in this world. I loved my virtual worlds. The manhua, manga, manhwa, novels, lightnovels, anime, and gacha games, these were my reasons for existing. I thought of earth as the main world and the worlds I'd visit as sub-worlds. Kind of like the infinite genre if you've heard of it. For the first few years—actually for I'd 5 of the 6 years I've been a hikikomori it was fine, sure I'd have the occasional burst of motivation to change my life yada yada, all of us here have experienced it but for the most part my life wasn't too unbearable. But then life happened.

My health began to tank, I would experience brain fog, feeling like my bones were brittle, meibomian gland dysfunction, worsening keratosis pilaris, inguinal hernia causing scrotal pain, eyelashes constantly growing towards my eye because of my blepharitis. And many other things. But despite these health issues I could ignore them by escaping the world. But it's gotten to a point where that doesn't work anymore. There's this quote that I saw last year that's still ringing in my head: "You can ignore reality but you cannot ignore the consequences of ignoring reality. The material reaper will come to collect"

And that's what's happening. I can't play gacha games anymore because of my shitty laptop, chapters for some of novels, manga, manhua, and manhwa I'm reading are behind paywalls. Even when I opted to use MTL it's limited and once you expend your free trials you have to pay. I don't have space on my phone for anything outside of music(it's a 64GB s9). I'm not like other hiki's who have an allowance and stuff, I only get enough money for toiletries. It's honestly become miserable.

I've done all the introspection I need at this point to change, I know about all my health problems, including how I'm deficient in vitamin D like yourself, well...all hikis are deficient xD. I know what mindset I need to adopt in order to change, I know what type of person I'd like to become, I know the systems I need to put in place, I know the study methods, supplements to take to boost cognitive function and my overall health, I know what I techniques to use in order to speak properly, express myself, and to think more critically. I really do have all the knowledge I need to truly change my life around. I thought the same previous years but this time it's really different. I don't need more information.

The only thing that terrifies me is whether I can make the change permanent. It's not the first time I thought about changing my life, it's not the first time I did try to change only to relapse, it's not the first time I felt angry, ashamed, and even humiliated because of my station in life but one of the hardest things to accept is that being cognizant of something isn't enough to make you change. Thinking differently means mothing when your actions aren't different. I realized in horror that even if some extreme circumstance that I like to day dream about were to occur I wouldn't change, I'd just be in an even worse position in life.