Dear lady, I feel for you, but I honestly doubt that anything you do or say now will change this relationship.
Neither your son nor your daughter-in-law is taking your feelings into consideration.
I would tell them both, preferably when they are together and face to face, that you very much want to be part of your coming grandchild's life and ask them how they envisage this happening?
If they look at you blankly and ask what you mean, point out politely that they seem to spend a great deal more time with her relations than they ever do with you, and you would very much like this to change. See what they say.
Here comes the part of my advice, that I am afraid you will not like and therfore not consider taking.
Spend less time worrying about your son and his wife. Make new friends, take up various hobbies, if you are retired, get a dog or a cat - do anything in short to give yourself less time to brood over a dysfunctional relationship, which you cannot alter unless the others also want it to alter.
Some of us unfortunately do have children who decide as adults that they do not particularly care for us. This may be what has happened to you.
I am much afraid that you caused a rift when you voiced your original criticism of the woman your son was in love with, or rather her relationship to her mother's family and lack of one to her paternal relations.
If this is the source of the trouble it will be too late to change it now, unless of course these selfish young people decide you will be a useful baby-sitter!
Bluntly speaking, Get a life and let the young people sail their own sea. Doing so, might just work a miracle if they see you as clingy and needy. I am not say you are either, but they may perceive you in that way.f