i don't think you've chosen the wrong path at all. there's no point doing anything if you don't love it, and you should definately do what you love, as for going to school, you can go and study it any time you want, if not now, then maybe in 5 or even 10 years.
as for looking after your brother with your dad, it sounds tough, but i don't see why you couldn't get a short term job to help bring in an income, and there is such a thing as compassionate leave, so you could always take time off to look after your brother.