I'm wondering about the 'not depressed' thing too. Because from how you are responding, OP, and what youre saying, that's exactly how it sounds. Depression isn't just sitting down feeling sad.
So you've mad bad decisions in the past and now you're trying to square things with yourself. Okay. Then you need to try to work out what will make you happy. And of those things, what are practial, what can you actually do?
You have debt. Is it manageable? Can you look into alternative ways of paying it back? Could you declare yourself bankrupt and start with a clean slate?
You say your finances are chaotic and you won't have a mortgage. But why do you want one? If you live in an expensive area are mortgage repayments that much different from rental rates? What would you do with an owned property that would be different?
You don't have kids and that's a source of regret. How much do you want kids? Is it really too late biologically or 'too late' based on your family and peers? You don't have to be in a relationship or dating to have kids if that is something you really want. Again, if you did have kids, how would this affect your finances, your job, where you live?
You say you can go weeks, months without speaking to people. Does this trouble you? Is this because of the nature of your job? Is it because you don't want to speak to people? Is it because you think people find you unapproachable?
You don't have to answer these questions, at least, not on here, but I'm trying to understand the reasons you feel you have messed up your life.
It sounds as though the expectations that are oppressing you are partly formed by what is deemed to be "the normal" and you feel you don't conform to that. But why do you want to?
When I was a teen, everyone was dating from age 13: I wasn't. Everyone in my peer group had had sex by age 17:I hadn't.
The majority of my friends went to University: I didn't.
Everyone in my peer group was in a serious relationship by 21 and had moved out of the family home: I hadn't.
The majority of my friends were married and had kids by 25: I hadn't.
Many of my friends had an interesting career, which they enjoyed, by around age 30: I didn't.
Many of my friends now are grandparents: I'm not
I have an outstanding student loan (taken out as a mature student) which I doubt I'll ever pay off. I have a young child who I may not live long enough to see settled in a relationship. I don't have a career. Right now, I don't have a job.
However, none of these things bother me. It is not my responsibility to fulfil other peoples' expectations. What is right for me isn't necessarily right for other people.