Every 6 to 8 weeks.
Me too, I have a hard time with hairdressers who want to cut too much but I found that the ones from cheaper salons tend to ignore my plea to keep it longer. Why? Maybe in high end salons they assume the customers have the money to sue them?
This said, a high end salon is absolutely NOT a guarantee.
One strategy is to visit your stylist for a blow-dry in between cuts, so the hairdresser has a better feel of your hair, your tastes, your hair goals.
In my personal experience, I have found that the hairstylists who respected my wish to grow it tended to be women.
Really, it's time you look for someone else. My advice is that you spot women around you who have amazing hair and ask them who is their stylist.