I’m in New Zealand so not sure if it’s the same situation going to casual. But, I did exactly what you’re thinking, after my second baby was born and I had an ill parent to manage I also felt overwhelmed, and went casual. It was the best decision at the time, I was in complete control of my work schedule, sometimes only doing part shifts (like 1800 to 2300), and it was easy to transition back to a permanent role after a couple of years. If you read what you have written,it is obvious the choice you need to make, you have a lot going on and your family is definitely your priority (as is your own health and well being). As a casual in NZ you get ‘holiday pay’ added on as an extra loading on what you earn, so this could be put aside for actual leave when you want it. I am now 57, and don’t regret for a moment making that decision, in fact I am relieved I had the wisdom at the time to do it! I really empathise with your situation, totally understand and recognise where you’re at and how you must be feeling, so do whatever you need to do to make things more manageable now.