Hi @maria1970
I too am triple positive - and like @sawabev am on the HER-2 thread which is super helpful (though be warned it has over 2000 posts so be armed with a cup of tea if you plan on reading through the history 
)
I think this link will take you to it: HER2+ and need some buddies
When I was worrying about the time between diagnosis and surgery (which in my case was about 6 weeks and I think just slightly outside of the NHS target) my specialist nurse told me that although my tumour was fast growing, it would still take 2-3 months to double in size, and that even if it was double the initial size it would still be very treatable. In the end, the lump removed was sized in the lab exactly the same as was predicted by the MRI.
Don’t know if that helps any but your team will have seen sooo many people in a similar position to you and will be working together to help you have the best possible outcome.