health anxiety and getting others to stop talking about medical stuff

Hmm I assume your mother already knows about your health anxiety disorder, but maybe you can remind her how much such things affect your psychology? If she knows you worry over such things a lot, then maybe she will be more careful...

I have similar problem, though, my relatives are trying to convince me that one can never be sure about their health, can never know what's gonna happen tomorrow and therefore there is nothing to be scared of even if one gets dx ed by C. They want me to accept everything in life...
This is their way of telling me not to worry, by saying how people just die with a terminal disease, even though they just got check up 2-3 months ago with negative results!

This absolutely doesn't help. NO, it doesn't help. And I tell them not to tell me such things, but they do it anyways.

Yes, my family "struggles" with my HA! They get irritated, when I share my worries... They get literally annoyed.
They think they help by sating such... but no, we are all alone with our psychological issues. That's one fact we need to accept, and others will never understand how we feel.

Only professionals maybe... Do you get help from therapy?
Probably they give you best help.

Hang in there, sending healing