It does not seem a problems of communication, you certainly do it more effectively than me, but maybe a problem of expectations.

After all a first session is mostly about establishing trust, both ways. My seven could be somebody else's 4 or 10, and it is understandable that a mistress is cautious before she knows you.

Personally most first time session experiences were like yours, but on occasion I had mistresses trying to break me when I did not ask for it.

The best mistress I knew, and I met her when she was at the top of her game, did not ask me at all, she tested me, very efficiently and speedily starting very gently and reaching the perfect level.

However that was a singular experience and I do not expect it to be repeated.