Am I too introverted?

Looking for peeps who could possibly relate to and also seeking advice on how I can come out of my shell a bit more.

I’m a 30 year old teacher, of course I have to be super talkative around students, but I find that I struggle with adults. Sometimes I find that I do not know what to say or that I’m just active listening. By the time, I feel that I have something to say about a topic, people are switching over to another one. How do I chime into conversations effortlessly? Sometimes I worry about sounding dumb or scared to be myself.