I'd say I'm the same as you(especially the regretting postings I've typed and to add deleting more posts that i've put on here, alonst this one), absolutely don't want kids though,. The career thing, I work I earn wages but ultimately just to pay bills I certainly didn't envisage this would be my " career".
I'm openly envious of people who go to work in something they enjoy( wife included to a point it's annoying) I wonder why I still do what I do and get payed, ultimately I like a roof and the opportunity to enjoy my weekends that's why I work if could stop I would. I see jobs advertised for roles I know I could do but like you I don't have the qualifications.
I've got to a point where I see people about me blagging it and succeeding which really annoys me, biggest problem for me is I can't blag interviews the same way I know others have.
I guess I'm fortunate, I have a house, a fairly dynamite backdoor but not a "career" just a job that I've learned fully but know it could easily be ripped from beneath me.
If this is rambling shite I get it I had to keep going back to your post to try and keep it relevant. If anything at least you got me to put my thoughts up. I don't know if this is what you want to hear but you are not a failure, you seem to be like many of us other folk who have just made choices that put us where we are.