Charge more and move upmarket. Work on your bedside manner and professional demeanor. For any kind of service work, my rule of thumb for how much you charge is “the highest number you can say with a straight face.” If they don’t like the price then you can work out arrangements where they buy X number of sessions at a 30% or so discount. When doing this always take the full price upfront, otherwise you’ll get people who just take advantage.
Take a cue from popular YouTube channels and ask at the end of every session for them to refer you to your friends. Without the repetition they’ll just forget, and if you keep it short and sweet then they won’t find it annoying.
It’s all about making the service you provide as repeatable, understandable, and useful as possible, then having the stones to actually ask to be compensated fairly. Always with a straight face, never get emotional. This is business and nobody ever got rich teaching meditation, but no one wants you to starve either. So just “man” up and ask for it.