Why do I never know what to say next in conversations?

I’m pretty friendly at school. I usually say hi/how are you first and compliment people pretty often, so I don’t think I have a problem starting conversations. But when someone actually starts talking to me, I listen carefully and I’m calm, but I genuinely don’t know what to say next 😭. I’m not even overthinking it, my mind just goes blank and the conversation gets awkward.

Sometimes I want to become closer friends with someone, but I don’t know how to keep the conversation going, so they end up talking more with someone else instead. I feel like other people naturally know what to say and how to keep a conversation going, but I don’t.

I also don’t know what to do with my facial expressions while I’m talking. How do people just naturally know what to say and how to react?

I wasn’t born in the US and moved here when I was little. I’ve been here for about 12 years, but I still don’t feel fully fluent in either English or my other language. Sometimes I feel like a failure because I can’t always translate important things for my parents, like at appointments or hospitals.

I feel like I’ve missed out on friendships because of this. Is this something I can actually get better at with practice?