Hi @GlitterGal and welcome.
The "hit by a truck" thing explains the initial stages of this perfectly. Of course with your mum's history you have an extra bit of awfullness thrown in on top of the mess.
This thing is hard enough and I feel for you with the ambiguous results. MIne was a bit like that at the beginning as well. Have you been given access to a breast care nurse? If not, ask for one. These ladies are worth their weight in gold. They can be your best advocate, explain all the medical terms in plain english, be a wealth of information and a shoulder to cry on.
BC treatment is improving all the time and getting control of this thing early is good. The shitty part is you don't really know what you're dealing with until it's out and tested and that involves a lot of waiting and a lot of sleepless nights.
You've come to the best place for warmth and understanding. No body can quite "get it" like someone who's been there.
Lot's of love sweets. You got this and we'll be there with you the whole way if you need us.
xoxoxoxoxo