Immagran We would all to help you if we could, but you seem to have fortified yourself in every way in saying that you are all right and your son and family are all wrong and anyone suggesting anything else is also all wrong.
I am afraid reading the above only explains why you are having the problems you are having. You are making all the mistakes that every thread ever on GN about being a grandmother warns you not to do. These include
1) Do not call in uninvited, or at least checking-up in advance whether it is convenient.
2) Do not give advice unless specifically asked for it. No-one wants to be told what they should be doing.
Your son and wife are adults and are entitled to lead their lives the way they wish without you constantly telling them what to do. They are also the arbiters of how you relate to their child. If they think that you will act with their child in a way that they do not approve of, then they have every right to limit contact.
3) It is not unusual for a new mother not to want lots of help from grandmothers. She wants to gain confidence in caring for her child in her own way. Child rearing methods change from generation to generation so what you 'knew' when you had children will no longer be relevant or correct and the last thing she needs is grandmothers trying to make her do things that are no longer considered safe and acceptable.
4) Parents have a right to decide how often grandparents visit whether you like it or not. You complain that you only see them a couple of times a week How often were you expecting to see them, that sounds more than enough. They are a family and want to spend time together, without one member of the family deciding they can drop by whenever they want to. What if the other grandparents expected to act like that. Your son, wife and baby would have no time to themselves.
5) You seem absolutely convinced that everything you ever did was right and others are all wrong. The fact that your children spent lots of time with their grandparents, does not mean you have a right to see your grandchildren. I am sure if you had thought your children's grandparents, might do harm to your children or cause strife in the family, you would have limited contact and that is all your son is doing.
I am sorry but the more you write about your situation the more I end up understanding why your son is acting the way he is. As I said in a previous post. All you can do now is stand back, get on with your life and hope things improve. Meanwhile reread the responses to your post carefully and think about them. None of us is out to get you and we all want to help you but, currently, you are your own worst enemy.
As a general rule grandparents with good relationships with their children, visit only when they know it is convenient, do not buy presents unless they have checked with the parents that the gift is acceptable and appropriate, do not give any advice, and accept that their children are independent grown-ups who will almost always do things differently to the way they would choose to do things themselves.