I wonder if this has to do with dependence and/or control.

Being independent and not relying on anyone else is a big thing for me. I have learnt in the past when you depend on someone it allows them the opportunity to let us down. I feel that if I keep stuff internal I have more control over it. I hate feeling that I need to tell someone or even worse that I can't handle stuff on my own, its a power struggle for me. I also don't like the fact that sometimes between sessions I feel like I want to contact my T to tell her something, I usually resist the urge and it passes.

These are just my thoughts, they may not be relevant to you.