Thank you for your question.
People some times see their grandchildren everyday it depends on how involved the grandparents are in the grandchildren's life.
Some times people tell their close friends things but not all of their friends.
She seems like she likes to fill you in on her life because she likes sharing things with you.
She also did not mention her knee because I think she did not want anyone to worry about her.
She sent pictures all month and e-mails so she is constantly in contact so I feel that you are very close friends.
People do not share everything and when someone shares a lot of their life they consider that person a true friend that they trust and care about.
It sounds like she does not answer all her e-mails because she is so busy. I do not feel like she wants you out of the picture I feel that she wants to be friends and you are important too her.
When people do not want to be friends they just do not respond. They do not e-mail, write, text, message, call. They just move on from the friendship.
This is not happening her she is sharing her life with you.