No, you are not being unreasonable. Your health and peace of mind are the priority here, and your Mum is a worrier, so you will have no peace of mind if you tell her.
Unfortunately, she will be hurt, but you can only try to minimise her hurt by telling her that knowing that she would worry too, made you decide not to tell her, as you felt worried enough yourself.
I'm sure you don't need to worry and please do take care of yourself after the op.
To obliterate your address on packaging
Being moved along by someone who "wants your place".
How much do you spend on yourself?