This is my situation too.
I have a disabled DS who is 14 years old and still in nappies. Needs support day and night, and can't manage any activities on his own, including washing. His twin sister is also disabled, and has reasonably high care needs too.
Both children are now home educated as there simply isn't spaces in the local SEN schools. So they are with me 24/7.
My DM, who lives in an annexe attached to my house, has cerebral palsy. I am her carer.
DP collapsed at work two years ago and will never be able to work again. He doesn't need "care" most of the time but his condition means I can't leave him alone in the house, and he can't go out without me. He can no longer drive or do the majority of chores around the house.
I work as close to F/T hours as I can manage. But that means working through the night. I am often up working until 5 or 6am, in between going up and down to both my DC. My DD normally needs me intermittently up until around 3-4am.
I cannot tell you how utterly, utterly exhausted I am. Or how broke we are. But if I don't carry on, everything will come crashing down and we'll have no home. So I struggle on actively caring for three people, and heavily supporting a fourth. And working in my self-employment.
I get UC. If I claim Carer's Allowance, it comes straight off my UC, pound for pound so I'm no better off. So I didn't bother claiming Carer's Allowance because there's no benefit.
Being "allowed" to work more for Carer's Allowance makes zero difference to me and the many, many carers in a similar position.
Carer's Allowance is taken off your UC so whether my earnings are £145 or £190, I won't see a single penny of my Carer's Allowance anyway.