Dear OP. I'm glad you posted for support. I know any old stranger can post 'it's not you, it's them' on the internet to comfort you, because it seems the right thing to say when someone has written that they feel so low. But from what you've posted I genuinely believe this is the case.
First thing I'd say is that hospitality is a notoriously cutthroat, brutal industry. It's well-known for it. And so - without meaning to stereotype but it's inevitable - are chefs. Shouting and swearing at people really isn't a good look.
PPs have also made some excellent points about possible ADHD/autism. It may be worth investigating.
I was once like you. I'm no slouch intellectually, but I have the one blind spot that if there is such a thing as numerical dyslexia, I'm a prime candidate. My maths are atrocious. I can barely even use a calculator. I once had a job as a data-input clerk. I inputted numbers onto spreadsheets all day long, unremittingly, until my eyes crossed over and felt like balls of glue in my head.
I can proof-read written texts very accurately (which is fortunate as I'm now a writer). Proof-reading numbers was simply like churning around incomprehensible symbols to me. I wanted to print the finished product off so I could compare the figures accurately against their source but was told 'no, your check is on the screen'. My manager was a horrific bully. She harangued me relentlessly, treated me as some kind of bimbo (her words not mine) and eventually fired me for incompetence. It shot my self-esteem: my intelligence was the one attribute I'd ever felt I had going for me at that age, and this situation caused me to question whether I really actually was terminally stupid. It was one of the most humiliating experiences of my life. So much so, that until now I've never even told anyone else about it.
If it's any comfort to you, OP, I'm now an academic, working in a subject that's my true niche (it isn't maths or the sciences)! I have a Class 1 Hons degree, a Master's with distinction and a PhD. I consistently publish world-class research (3 and 4) and my name is well-known in the scholarly field of what I do. I'm on course for a Professorial chair.
But I sucked at numerical data-input. I also sucked at bar work. You too can find a profession that's deserving of your own particular talents and abilities.
You're not stupid. Keep telling yourself that. Your self esteem is taking a bashing because you're being bullied by arseholes, and if your experience is anything like mine, the more you're bullied the more the cycle continues and you fear making more mistakes, so the more 'incompetent' you get. In any case, everybody makes mistakes sometimes. Your oh-so-lofty employers are not perfect in this respect either.
It's not you. I promise you, it really isn't.
(PS. I have endometriosis and once felt the same way about that as you do. I did have a child, as do lots of other women with the condition).
One last point. I went to university as a mature student, not straight from school at 18. I was 25 when I started. Office work wasn't cutting it for me: I was bored and dissatisfied with the work and rarely lasted more than two years in any job. It's possible to change your life's direction at any time.
Sending you 