Thank you for your Question.
I’m in short of words for a brave and strong person like your noble self! May Allah increase your strength and bless you with the best in both the worlds.
I’m sorry to hear about your mother and hope she recovers. It is very difficult to see parents being ill and bed ridden.
As for your question, yes Allah has power over everything but that doesn’t mean that by clearing out someone’s medical issues HE proves his power. Everyone has to leave the dunya, we are all lined up, one after the other, some have very strong and vivid reasons while some are taken by surprise. The whole idea that we all must be able to digest is to believe that this Dunya is not the final abode and there is more for our souls.
We don’t die die when we leave this world. Our soul just leave the body and goes to a better and freer place.
However this dunya has a great impact on our next level of life. The amount of good doings you have earned here, your struggles and difficulties all count there.
In your mother’s case, she has suffered so much and our hearts ache to hear about her, but on the hind side, her difficulty in this temporary station makes her permanent life better. It is kind of paying off for her to have a better Akhirah. Since she has suffered so much already InshaAllah Allah helps her to have an easier next life.
The above is my words of understating, however Allah is the best planner, HE can surely fully restore someone’s health and vice versa. But whatever is decreed for one, it is to be for the best, as Allah is the BEST OF PLANNERS! All we can do is to pray for her and do our best to take care of her.
As for yourself, suicide is a cowards thought. And hearing about yourself and how brave you are to take care of your mother, doesn’t sit well. I suggest you take some counseling or speak to a local scholar for support and further guidance with motivation.
Also, as you mentioned, you have a sister, and she can be a helping hand while you catch up with a bit of rest and beak.
Yourself and your mother are in my prayers