Take anything I say with a grain of salt because it's just one stranger's opinion, but it sounds like you feel there is nothing left for you to do in life but have a baby so you can try to succeed at something. The thing is, though, that anyone can have a baby - being a good parent and/or enjoying it is another story, but just plain old getting pregnant is something teen girls do with no effort at all in their date's car on prom night. Would any feelings of success be long-lived knowing you accomplished something people have been doing out of instinct since the dawn of mankind?
Babies won't make you feel better or more accomplished - if anything, they will place further physical, mental, emotional and financial burdens on you. Odds are, you will feel worse caring for a child, and I would also be concerned that you are essentially giving a potential baby a job before it's born: the job of making its mother feel better. When the child fails to fulfill the obligation you place on it, you will begin to resent him or her.
No one's holding a gun to your head and saying you need to have a baby right now. Honestly, you in no way sound like you're ready for one. If you get past 35 or 40 without having kids, why not adopt or foster? A baby's a baby, right? If you want a perfect white baby, you might have some trouble, but children of other ethnicities or who are older than freshly born are easier to adopt.
Maybe there's a way to get your kid fix without subjecting yourself to two decades of servitude. Far, far too many women listen too much to the biological clock and end up resenting their kids and regretting having them because they didn't take much time to think about their choice.
I hope you may find something that makes you feel fulfilled - I really doubt it's parenthood, though. That's what a vast majority of people turn to when they think their lives aren't complete and I'd say in at least half of those cases, having kids made them feel more empty than before. And when you're stuck with a kid you regret having, you can't give it back like a shirt that didn't fit.
I apologize if I'm being a pessimist - I just personally do not see a child making you happy and I'd hate to see you dig yourself into a deeper hole. Like I said, take my words with a big grain of salt; I'm child-free and I guess I just naturally do not at all see the allure of a child. However, that doesn't mean I don't understand what it's like to feel useless, to get fired (or not hired at all) from everything and to just feel like I'm going nowhere at all. I don't have any physical ailments, so I cannot relate to that part.
If none of what I said is helpful at all, then please accept some digital hugs and just me hoping you can find whatever it is you need.