Where all are you advertising? You might want to ask the ladies in the ladies-only forum how they’re maximizing exposure. One suggestion I’d make is to post some photos in the new gallery that was introduced earlier this month.
Also, are you a member of P411 and OH2? Nowadays you can’t depend on just one site (if you ever could) for advertising.
FWIW, I rarely spend more than $$$ on a session, but there are ladies that charge higher who seem to do fine. I suspect they want fewer clients, and well-heeled ones at that, so they keep their prices higher with that goal in mind.