First of all, allow me to say I am heartbroken about your mother’s health issues and I wish her a complete recovery. I know words are empty when someone has serious problems, yet I care.
I think maybe you should ask someone in person and everything would be much easier. It’s not difficult to observe Shabbat for someone who wants to, while 200 years ago it was. But your situation is different, because you don’t know the rules and how to do. Also I would not discount the comment of zahavasdad, which asks you if you plan to get bored in the house for the whole day, possibly in the dark or in the cold. It is my opinion you have to think of the seemingly simple problems, because they are important in the long run, and make the difference in committment.
Are there other jews where you live? Consider that older people are likely to have had some sort of jewish education, also secular jews with secular parents used to; someone who is aware of the basic laws could give you suggestions. Take everything with a pinch (or a handful) of salt, it goes without saying; but you seem to be completely alone, which is tremendously difficult.
I have not understood why you are not asking a rabbi, and if it is your choice, or contingent problems (all of those can be easily solved).
The other thing I have not understood is what your mother thinks about all of this.