Reckon you need to redefine "joy" OP. You're constantly ill, your kids are constantly ill, you're stressed and about to lose your job. You're feeling guilty about potentially having to become a germ spreader and send your sick kids to nursery and go to work sick yourself. None of this sounds fun. I get that you enjoy the job when it's going well, but life isn't just about a job and the whole package deal isn't working. You're supporting DHs career at the expense of your own and that's a family decision you're all happy with. Except you're not actually happy.
My solution: stop trying to be all things to all people. You're not superwoman, she doesn't exist. Stop trying to protect other parents and their children from germs. Stop trying to prioritise your employer over your health by going along with their unrealistic healthcare practices. Stop accepting the status quo from DH.
Stay home, raise your kids. Everyone will be healthier and therefore happier. You can support DH career even more than you do now. In return he can support you better.
Firstly by paying into a pension for you and voluntary NI contributions so you can get a state pension too.
He can take annual leave on occasion to stay home with the kids while you do some kind of industry training to keep your hand in, so your skills and qualifications don't become obsolete (he can pay for the course, any travel and accommodation costs). Then you can return to your career when life is less hectic and sick kids can be left on the sofa with a blanket, remote control for the TV and a lemsip while you go off to work all day. 10+ should do it, if they're genuinely sick they won't be getting up to mischief and if they're less sick they can have some paracetamol or immodium and go to school.
DH needs to realise that if he wants his career prioritised that means he steps up and provides, for you as an individual, not just for the family in a bare-bones way. This includes access to a joint account for daily living expenses and also some of his salary paid directly into your own account from his on payday - for personal spends on whatever you like, with no justifying it to anyone else, or saving it into your own savings account for a rainy day if you prefer. You don't have to have a job to feel independent, just a good DH who's willing to truly share.
If one salary means you have to cut back as a family then that's what you do, all of you. Not DH keeping his chosen standard of living and the rest of you scraping by, feeling guilty for buying anything that isn't essential food or the gas bill. If you need a cheaper house, sort that out. If he's amassing huge savings/or putting into his own pension by an excessive amount, and that has to stop to free up some funds so you can have a pension/some personal spends too, then so be it and he'll have to cut his saving back. So that fucks up his retirement plan? Tough shit. You had kids together and that's fucked up your career. It's time for him to eat shit too, it's not all on you.
You're currently not really working as a team. Which is shown by the fact you're on here looking for a magic solution that doesn't exist instead of talking to your DH about practical solutions for making life work. Go talk to him and tell him to pull his finger out, because he can't have it both ways. He can't be the priority and do the bare minimum childcare/school/ sickness duties, while you work yourself into the ground supporting everyone except yourself - all in the name of feminism or girl power or independence or whatever else you've tippexed out the word "mug" with and written in it's place.
I'm not saying he's a bad man or bad DH or doesn't care etc. Just that he's so far been a bit cushioned from the realities of life and parenthood, by you. It's time to unveil those realities and have a conversation about how "equality" doesn't mean one of you scrabbling around all over the place trying to make a situation work that just doesn't. You don't have to be the same as him to be equal, but you do have to work as a team. If he's a decent man he'll listen and be willing to change.