OP, now you have told me a lot about the situation, I think you need to think about your own family and prioritise them, and if that means moving away, so be it. You've said so far that you have moved near your parents to help as they age, that you moved in for two months already to help your dad last year, and yet, you yourself have had cancer and lost your house, but your parents did not give you money then and aren't helping you now.
Adding this up with the fact they never gave you money at uni, just saying 'get a job', I suspect that the kindness in terms of real life sacrifice is only going one way- they like to do the odd lunch, which is still kind, but not on the same scale you are offering.
I would make sure that given they are very much saving their money for care needs, that you simply don't just step in and do all the caring, or live in an area that doesn't suit you and your family (and is expensive) unless that's what you genuinely want to do.
I can't understand this type of thinking, people saving for care costs when they have an excellent monthly income from their pensions, plus the state pension, plus investments, plus heaps in their current account. They are loaded- and don't want to share, and given this isn't a 'sharing' type of arrangement, I'd make sure you are truly giving and not just doing what's expected.
I do everything to support my children financially, my mum did with me and they in turn will support me and each other- it's how we are, and if it's not like that in your family, make sure you are not disadvantaged.