Amina, you are so brave, and so very, very kind and loving - your mum has a WONDERFUL daughter, and I only wish she appreciated it more, by caring for YOU, and caring ABOUT you more than she clearly does. Depression can, sadly, make people behave very badly towards others - not out of malignity, but because their own unhappiness blots out everything and everyone else. I believe the term for it is 'self-focus' - only their misery counts, only their unhappiness, only them, them, them.....
I do think, you know, that you now have to be 'the parent' and take the decisions - yes, the tough ones you say are scary - that are necessary. Your mum really is not in any position to make them rationally or fairly. When children become their parents' carers, at any age, they actually have to become their parents' 'parent' and 'take over'. I think this is what you are now starting to do, and I think it is the right thing, both for your mother, and for yourself. I'm glad you took her to the doctor's, and got her back on her ADs, as this must surely help - help her AND you (it will help 'shelter' you from her a little I think.) The next thing is to turn your attention on yourself, and start the process of booking extra help from outside, including getting in a carer to take some of the pressure of caring off you. Professional carers have 'seen it all' and know perfectly well that so many times the 'caree' (your mum) doesn't want them there, and wants their daughter to do everything etc. But as your mum gets used to a 'stranger' then the 'stranger' will become familiar to her. And when you are less stressed and exhausted there will be less tension between you and your mother.
It's hard to change our lives 'totally' or 'all at once' but if we can find 'little ways' to start making inroads into the 'sea of unhappiness' engulfing us, then little by little it can ease, and the pressure starts to 'lift'.
Now, having got your mum to the doctor's, and got her back on her ADs, what is your next step? Keep us posted!
All the very best to you - because you deserve it (you may well not get 'the best', as life seldom gives us that, but I very much hope you will 'get to good', or, at least 'less bad'!!!!, before too much longer.)
It can be done, and you can do it.