I am so sorry to hear about your loss. This must be a very difficult time for you.
I am also sorry that your best friend has not provided the support you would have thought she might.
I would echo what has already been said by others on this thread.
Your friends reaction is a result of a lot of things, her own life experience, her job as a GP and her own issues with possible loss previously and in the future.
Many people find talking about death and dying very difficult. Because they do not know what to say or how to say it they say nothing. This is so awful for the bereaved person. But is no reflection on you at all.
Have you considered making contact with your friend? Perhaps she is feeling bad about not contacting you now and because so much time has passed does not know what to say? This would be an opportunity for her to support you. If she does not then at least you know where you are rather than being left wondering?
As you have said you are grieving for the loss of your mum and the loss of your friend.
My thoughts are with you at the moment and although you will always miss your mum, you will begin to feel more positive as time goes by I am sure.
I hope your friend is able to offer some support for you. It sounds like other friends have shown themselves to be worthy of your friendship.
All the best.....