Ive read the entire OP multiple times. I hear the frustration and loneliness.
I also paid close attention to what you said about the forum and would like to offer my perspective. You may or may not value it, either way is okay.
First, I observe that you have been noticed. You have an exceedingly high number of reacts for a low amount of posts. You must say things that people connect with in some way. You have six and a half times more reacts than posts. In comparison, I have 1.7 times more reacts than posts. Admittedly, I have not looked at the threads you've commented on to see if anyone regularly engages with your comments beyond a react. However, you recently posted a question about F, and you got a lot of thoughtful responses. I've been active on the site for close to three months and from what I've seen, you got quite a healthy response. I also looked at the first page of your post history. I noticed you post on people's walls. Only one person did not respond who has been active since, and one person responded with an invitation to reach out any time. Maybe you did and it was a dud, I have no way of knowing how it turned out. In summary, you are noticed on this forum, you are not ignored.
I also note that react-to-post ratio is where the comparison between us should end. I'm gregarious, extroverted, social, and interactive by nature. I post a lot, that is my way in any forum I've ever been on. I'm not particularly loved or admired, but likewise I do not particularly love or admire the majority of people in the world either, and I'm content with that, but it took me many years and a lot of work to achieve that contentment. (I'm a 49yo woman btw.) I'm just my authentic and imperfect self here as much as I am irl. My self is very different from your self, and I'm completely accepting of that, no comparisons, no valuing one of us more highly than the other on my part.
Another challenge is that this is a suicide forum. In my observation, a great majority are here for less than three months, and their primary focus is to get information to work out a method, and get support to work out whatever shit keeps them from or causes them to ctb. If people make a deeper interpersonal connection than comments, I think it's generally because at least one of them gets something they value from the other person, are seeking the same things and happen to be members at the same time, and/or they share a particular affinity with the other person based on one or more similarities like age, conditions, beliefs, method, life experiences, interests, hobbies, background, goals, etc. I observe that making such a connection is rare for me personally because there are not many people in my older age group, and who also share similar interests, so I don't do much PMing. My interactions are overwhelmingly on the public side, and I connect briefly with a wide variety of people. For the most part, I've had some approach me privately for an opinion, advice, or insight, or I reach out to them, we discuss, and then the subject is closed and we each move on. You and I do not share much in common. I respond to you in comments as I do many, I notice and read many of your posts, as I do others', but I don't feel badly that there's nothing that stands out as affinity between us, and I don't consider it a rejection of you in any way. In turn, I don't think there's much about me that would attract you, and I'm okay with that too. But I have noticed you, and I certainly don't reject you as a human worthy of connection.
In short, SS is predominantly a place of moving on, and deep interpersonal connections seem to be far more the exception than the rule.
I can't fix any problems for others, but I can share my unique personal perspective and life experience. When I look at your desire to be noticed and connected with, I can't speak much to your irl experience. I don't have the same challenges and conditions or, from what I've noticed so far, background. The only thing I can speak to is your desire to connect with others on a forum. Since this is a forum generally consisting of brief connections, primary self-focus with secondary other-focus, based on mutuality of methods and desires, and in general, moving on, I think your desires will be frustrated here. However, I would offer that you're on the right track, and ask if you've sought out forums for people with your challenges and conditions (such as autism, for instance), your particular background (bullying? parental abuse?), and your interests. It seems that you have the ability to reach out, perhaps it would garner more satisfying results on a different style forum. I'm not at all suggesting you get the fuck out of here, I'm sharing my observations of how the forum operates, and suggesting that if it doesn't meet your needs, it's not that you don't have the interpersonal skills to achieve what you want, nor is it impossible, only that you may need to seek a different venue that's more suitable for those desires and needs.
That was a long and thoughtful response, in which you definitely weren't being ignored, rejected, or not cared about. But if it wasn't beneficial in any way that you value, that's okay. Like I said, I can't fix anything. I'm just acting in my interactive, extroverted way. I sincerely wish for your well-being, and, ultimately, that was at the root of everything I said.