and of course child-free wedding
I'm not sure what you expected to happen from suggesting a childfree wedding. Daycare can be quite expensive for some people. If anyone is out of town they might have no choice but to bring kids.
There was no/little comments made for us about being childless
I'm sorry your family seems more affectionate towards your cousins now that they have kids. That sucks. But being childfree isn't something you should expect your family to be proud of you for. It's what you do with the opportunity that matters, and going on vacations generally isn't something you should expect praise for.
because she gets jealous of us living better life than they
Wow. Do you know how that makes you sound? Lots of people either can't afford, or aren't able to go on vacations and don't want to hear about yours. It doesn't to be about childfree vs. having children. If I have a friend with lower income, I might limit the amount I talk about an expensive vacation compared to a friend who could easily afford it. That's just common courtesy. If they aren't interested in the topic, then you don't talk about it.
I hate saying this because it's a sensitive word here, but overall you seem selfish. Not because you're childfree, but because of the extent you expect others to accommodate you for it.
I'll end this with a bit of advice. People often have disagreements with family on basic life views (athiesm vs religion, having children vs being childfree, hillary vs. trump, brexit vs. remain). Most people are stuck with their family and can't easily "choose new families" any more than you can force someone to think of you as family instead of a friend. Being childfree is no different than any other major conflict that can utterly tear families apart. I have friends that are actually estranged from family over their anti-trump stance. Do what everybody else does. Thicken your skin, tell them your stance, and tolerate the environment as much as you can enjoy their company. If you can't stand it anymore, then don't see them anymore.