I find small talk hard

I work with children and four other adults. I find at the start and end of the day my colleagues make small talk and though I can mask and do some small talk, generally, I don’t have a lot to say and when I do talk I feel a bit of a black sheep as I’m participating but not actually a part of the group if that makes sense. It’s like I’m there but not really. I try to talk, copy their enthusiasm in what we’re talking about but to me it’s obvious I’m uncomfortable and not really sure why we’re even making small talk. I’m like this in the shops as well if the woman at the checkout starts to make small talk. Generally, I talk and can’t wait for the conversation to be over. Talking is not easy for me. It’s why I avoid phone calls if I possibly can. But, when it comes to work and playing with the kids I am at ease with this. It’s no problem. I find I am much better with kids than I am adults. I think this is partly because I still haven’t really grown up yet.