Hi Kath, really sorry to hear you've experienced this type dismissive attitude & social stigma.
My Breast cancer treatments haven't included Chemo so I can't say I know what the fatigue is like.
As a Mum & carer of a teen with chronic mental health issues I've certainly encountered the dismissive attitude & social stigma you speak of though many times - both in the medical system & out in public.
I soon realised that I couldn't change people's perceptions - only my reaction to them.
Sounds like since you wrote the post you're already moving forward with your new response, being proactive in pacing yourself & reflecting on how your Mum coped with her own fatigue - good for you xx