The charge for Greek is for the
access to 🍑 There's
diet we have to watch out for, and
hygiene prep of course, which applies regardless of how much "use" occurs.
Similarly, the PSE rate is for
access to those extras and the style/vibe during the duration of the session.
@Harmony-bc is correct in the standard calculation at (3*400)+200=1400.
Best choice would be to not try to negotiate further if you worry about the discomfort of asking. I agree that it could definitely come off a certain way, as you had surmised.
Would you consider a GFE date with the SP to gauge chemistry, and ask in-person instead for next time? You could also select a different SP you feel more comfortable trying to ask.