Sounds to me your husband has a very different relationship with his parents, even if you were closer can you honestly say the relationship would be the same, he’d be Popping to the shop, dog sitting, helping them out like his sister does?
You say you both don’t have the same ease as you didn’t live with them. But your husband did live with them, so clearly something very different in the relationship that’s not all one sided.
I honestly think the pair of you going down the resentment route and blaming them is not going to do any of you any favours.
You married a man who doesn’t have a friendship circle, isn’t fussed about socialising and isn’t very close to his parents. In parts of this Ie the friendship part, you are very similar.
Please stop focusing on them and what they all have what you don’t, and start to make the changes to your life that allows you to make friends, get socialising, find reliable childcare. It’s not your inlaws fault.
So start to think how do you make friends? Do you have old friends you have lost touch with? What about work, do you work? Anyone there you can reach out to? Local child groups to interact with other parents? Your local community, does it have stuff going on you could get invovlved with?
You need to make the effort, only you can fix it, only you are responsible for your own happiness.
I