My Mum has CVID and bronchiectasis. I had the BCG vaccination on Wednesday. I am currently at university, and I am meant to be returning home next weekend. However, I was wondering if I will be putting my mum at risk from the bacteria in the vaccine?

There is no concern about you putting your mum at risk because you had the BCG vaccine, she cannot catch TB from it. Take a look at this  link  for more information.