It sounds like you want to find a new therapist to work with, and it has been helpful in the past (even if only for a short amount of time). It also sounds like your biggest concern is having your dad know that you're seeing a therapist.

So...my question is....why does your dad have to know, if you're paying for it?

When I was in my early 20's, and living with my parents briefly, I was seeing a therapist and didn't want my parents to know and didn't want to discuss it with them. I scheduled appointments for right after work, and then would tell my parents that I was running errands after work and would be home late...or that I was going out with friends, or that I had some things to do and would be late. As long as they knew that I would be late, they didn't really question it. Maybe you could do something like that during the summer? I disliked lying to them, but it really wasn't any of their business either.