I would actually recommend a double domme session. The mistresses tend to spur each other on for more sadistic tortures. Don’t ask me how I know this.
You really will be happy with whoever booking recommends. FWIW, the most painful session I ever experienced came with Mistress Kang. But the dynamic of that session is what brought that on (it involved another mistress no longer at the Fortress). There are other mistresses that love to hear my screams. They would be more than happy to test your limits. They are all fantastic at what you are asking for.