It's important to find somebody your comfortable with but on the other hand if opening up is uncomfortable that may unfortunately linger with other therapists. Just something to keep in mind because you may come across someone who is great and you don't want that anxiousness to put you off sticking with them. It's kind of like when someone has social anxiety, in order to really fix that they have to socialize despite the anxiety. It's important for those people to understand if they feel anxious and don't want to go out with people it's likely the right thing to do. So in your case if you feel anxious with opening up to people you should know that keeping with it despite that feeling whether that's with this therapist or a different one is already a big victory towards your goals.