Never happy for me

[Newbabies15]

My friends can’t be happy for me. My twins are 4.5 months and my friend had a baby around the same time. We message each other and they regularly post about their kids. I do too but they never say anything positive about my babies. I’m always happy for them but they are never for me.

Are you talking about in real life or just social media? Is it just that they don't like or gush about posts of your kids while you do to theirs? If it is, you are way over investing in what they do or don't do online. Just because they are liking your posts doesn't mean they're not happy for you! Social media likes and comments are rarely an indication of people's true feelings.
It's very sweet of you to ensure you are commenting on their posts, but it shouldn't be a tit for tat. And don't assume that happy family posts mean they aren't having trouble adjusting to parenthood. They will be so wrapped up in their new dynamics they won't realise you are feeling insulted and ignored.
Meet up face to face and judge them by their real life actions.