It's strange how differently we see things, isn't it.
The selfishness of some adult children has been commented on, yet that isnt where I see the responsibility in this case.
It sounds to me, Akenside, like it was a recipe for disaster from the start, based on unrealistic expectations on your part.
"We did childmind for them 1 a week but was finding it financially difficult to travel every week"
"Although we did not really like where they lived we thought being near the grandchildren would make up for it."
Make up for it in what way(s)? Did you ask your son and dil's opinion on your moving so close to them, and whether your expectations matched theirs?
"they havent really been any support since weve been here"
What did you expect when they have a new baby?
I don't know of you intended it to, but your post makes it sound (to me) as if the move was all about you and what you wanted, but it was never going to work if the others were not on board with it.
I can't see any positives at all in your move from your son's point of view - you can't child mind any more than you did before, yet you seem to 'expect' more from them now that you live so close. You said that you were "^hoping the relationship would improve"^ if you lived closer, but under the circumstances, I don't think that was ever likely to happen. Quite the opposite.
If you can afford to, then I suggest move again, but give your OH a say in this.
If you decide to stay put, for goodness do not try to guilt-trip your son or put pressure on him to help you. He will have enough on his plate with his young family, without being expected to deal with the repercussions of your unilateral decision to move house.
Whether you decide to stay put, or move house again, just live your life and let them live theirs.
Make the most of any time you do get with your dgc, but don't push for more than is offered unless you want to damage even further an already strained relationship.
Whatever you decide, I hope it works out well for you all.