Op you can address this disappointment by doing the bare minimum in terms of visiting. Invite them along to your days out, parties and things at home and if they choose not to come, they miss out. I would not be stuck in their lounge every weekend serving their needs for entertainment with zero effort coming back.
It is an old fashioned by still very prevalent expectation that as their child you are there to do their bidding on their terms, that they have somehow earnt the right to sit back and let you do it all, on their terms.
That is what needs to change, you need to reset your relationship to one that is one more of an equal footing. They are no fussed to help, visit, get involved then fine they see much less of you all, and can forget about close bonds with dgc.
I have some advice as someone with late teenage children. Don't bother trying to explain this to anyone else, they simply won't understand unless they too have experienced checked out parents/grandparents.
Invest and take time getting the most wonderful and reliable babysitter so you can have fun, nights out and even nights away without worrying.
Gather a brilliant friendship support network that you can rely on and trust, so you can back each other up in emergencies. Stop asking your parents to do anything, they are using it as bartering tool. Ask anyone BUT them and then insist on a healthy adult relationships that is reciprocal. Take back your adult power. You can manage without them. I did for seventeen years.
My parents could not even be bothered to help in a blue light breathing medical emergency when my baby was four months old, at that moment I knew they would never be there for any of us - they are token grandparents, not real grandparents. Just fig leaves.
If you have a token gp cut them lose, don't ask for help, get the relationship on an equal footing, stop giving them your time and energy and focus on your young family instead 
You learn to accept it in time.