I know that it might not mean a whole lot coming from someone on the internet, but I would just like so say a few things. I've been in a very similar place for a very long time until recently, and I know how you feel. Between the cycle of wanting to improve and then hating yourself too much to even bother, I know it all feels suffocating most of the time. There's no reason for you to feel shame for these things, not even the suicidal thoughts. I hope you know that. The things you are dealing with are already rough, don't make them harder by blaming yourself for things out of your control.
You might not feel like you accomplish a whole lot, but you still trying your best to keep going forward while dealing with the demons you're dealing with is an accomplishment. You might not be the ideal version of yourself right now, and might be experiencing very heavily suicidal thoughts, but you're still here. That's an accomplishment, man. I'd argue that's the biggest accomplishment someone dealing with this sort of thing can have. And right now, you're accomplishing that at a minimum every single day. Be proud of this. Because it sure as hell isn't easy.
Baby steps can make a world of difference. A year ago I had a set date in my head to kill myself, and today I can happily say those feelings are gone. I was in that mindset for 8 years too. If you ever need to talk, you can always PM me. Hell, I'd give you my phone number to talk if you needed to. Just remember, this fight doesn't have to be just you vs. the world. Many people would have your back, mental illness isn't a joke.