It often goes one of two ways, even if piggies are close to each other. Some piggies will go quiet and pine, in extreme cases go off their food, while others get on with surviving, they do grieve but their survival instinct kicks in.
Our first piggies pitch and putt were sisters and unbelievably close, after pitch passed we were worried for Putt how she would cope, but she was absolutely fine, a little quiet for a day or two then it was like nothing had happened, unlike us who were in bits...
Keep a close eye on Amber as I am sure you will and when you feel it is time or she needs company it may be worth at looking to get her a friend.. Cookie lost her sister Treacle last year and while she was coping she was not herself so we bonded her into a trio with 2 rescue piggies.
I know everything is so raw at the moment and the pain of losing her is really bad, you will get through this. You really did everything possible, your little girl was so lucky to have such a caring mum.