im going to my first session with a psycologist for the first time...

hii so im 15 and for the first time ever im going to get proffesional help after a couple of years struggling with my mental health and physical health, my session is in two days and im really nervous, idk how its gonna go idk what to tell them and im just so nervous and overwhelmed. sooo i guess im asking for advice on how to not feel this nervous and im also kinda asking to know what to say or like what theyre going to ask for the first session. if you would like to give me advice or help you can do that by direct messaging me. thank you!:3