Most first sessions start with a silence. That is normal, and nobody is waiting for you to perform.
Three ways in
Start with the last time it was bad. Start with what someone else noticed. Or start with “I’m not sure why I’m here”, which is a perfectly good first sentence.
“I’m not sure why I’m here” is one of the most useful things a client can say.
Your therapist will ask a few questions to get going. You can say pass to any of them.