My mother is 57 with severe MS too.
I dont want to scare you at all just want to tell you my experience and give you my advice.
Id say from about end of 2007 to Feb 2009 we were fighting to keep my mum eating and drinking. We pushed it for as long as we could and to be fair to far. My mum began to loose interest of food and went down to 5 stone but it was her call to get the feeding tube inserted as you are aware its life changing and something we were all very scared of and especially her. But she got to a point when she knew she needed it and we had an appointment booked and we were prepared. So end of Feb 2009 we had everything booked and we were all ready as a family. Before this happened my dad took my mum on holiday where they went to a fantastic hotel and had their own personalised chef that pureed all mums food for her and had a wonderful holiday.
She came back and a few days later became un well. We did not recognise the signs of chest infections at that point and how serious they were as mum had never had one before. We called the GP and he came up and gave her cough syrup!!!
Next day were at a and e as she couldnt breathe properly and was admitted straight into ICU with Pneumonia and Septasimia. Was ventilated and had a tracheostomy fitted and we almost lost her. 4 months in ICU and 1 month in a normal ward it was a mirical she survived.
My advice to you and your wonderful mum that you know when the time has come to get the feeding tube. Like every step of this disease you adjust and get on with it. We thought this feeding tube was going to be the devil and be so heartbreaking. But its saved her life and has become the norm to us! We are in ouplic places and she needs water and we dive it to her without a secont thought! Its so easy. And honestly if we could go back in time we wouldnt have been so scared and just got on with it. Us prolonging things nearly cost her her life. We all went through the most traumatic experience and saw things that people only see in their knightmares when we almost lost her.
I am here if you want to talk properly about this. I promise it seems daunting, but her health is so important and it sounds like you are in the place we were. Dont put it off.
I send you so much love- i know exactyly what you are all going through.
4 years down the line my mums still fighting!!!