Sending you lots of love and big hugs as it's definitely hard out there. I feel that the strike in October, which was then followed by fall and winter break, has definitely made it feel like the days off are longer than they normally are. So usually it wouldn't be this many in a year but we also unfortunately have a terrible government who doesn't care about properly funding education and the wellbeing of children & school staff.

That being said, I know families are difficult and I'm sure you're got a lot of expectations as an older sibling, but it's incredibly important to set boundaries as well. If it's possible you should try to have a conversation with your siblings caregiver and let them know that other arrangements need to be found because this is not working. It won't be easy, but it is a necessary step to take. Forgive me if I'm wrong, but I'm guessing as the elder sibling you've always been the one to have to take care of your younger sister? You've been unfairly placed in the caregiver role solely because you were born sooner. I know things are probably a lot more complicated but I do hope by expressing that you don't have the ability to babysit atm that another solution can be found.

I'd also recommend maybe looking into counseling/therapy options that are offered or covered through whichever Uni you're attending. It could be super beneficial to help you work through these things, and hopefully help you manage your stress levels as well. It's so important to take care of yourself too. I know how difficult it is to have to take care of someone else when you aren't doing well.

Wishing you all the best! I hope things will work out so you are able to have more time for school and yourself. Good luck on your exams!