Honestly, it might be that she is stressing over her Ph.D. work and is not trying to snub you or hurt you. I got a Ph.D. and there can be a lot of pressure. So, my suggestion is to try not to take it personally, although I can understand that it would be hard not to. As you say, it sounds like you have many, many reasons to be proud of her.

I think it would be good if you can find other friends and activities until she gets a break and is free to chat. I generally let my adult sons call me. One calls often, usually with concerns or problems, and the other only rarely calls. I have to keep up with them on facebook!