Hard for me to talk in group situations

I'm fine with individual conversations and group texts but whenever I'm in voice call or in-person in any kind of group, even if it's a super casual one, I find it so hard to talk. Most of it is because I can't tell the right timing to say something, especially if there's good rapport going on between people, and other times I don't know what to say, so I'm silent 80-90% of the time. I really don't want to interrupt someone and it also makes me anxious when I do speak and everyone else is just silent and staring at me