Maybe think about why you’re hesitant to be fully open about it? Ex. Does it feel like you don’t want to admit something happened, you’re embarrassed, or just don’t want to think/talk about it anymore? Or is it that you feel like that he’s going to judge you or react in a way that makes you uncomfortable? Because if it’s something along the lines of the latter two, then maybe think about trying to find another psychiatrist who you feel more comfortable with. But if it’s along the lines of the first three, I’ve been there and I find that once I figure out why I don’t wanna talk about it, that gives me a good place to start from to figure out how to approach the situation.