I'm so bad with friendships

I have no real friends, I told one of my only friends my diagnosis and she's been really cool with me since. I'm 38 and I have three children, a dog and a husband but I feel so lonely sometimes. The school run in particular is the worse, everyone is chatting and I feel like they're talking a different language. It gets me down so much, I try and have a duck it attitude but a lot of the time I'm trying to work out what's wrong with me, and hating how awkward I am. How do you make friends as an adult? I've joined FB groups and even my local autism group but I can't navigate the whole be my friend thing.