I'm often fully booked weeks in advance and only treat females. Do you have a website? The majority of my new clients find me online. My website allows for online booking too which many of my clients say makes the booking process so much easier (plus means I can take a deposit, win win!).
I see you do pregnancy massage. This is by far my most popular treatment, I also offer pregnancy facials and pregnancy pedicures (not sure of this is something you would ever consider??) so I get a lot of ladies booking in for pamper packages. I'm positive this wins me clients over other prenatal massage therapists in my area.
I contacted a pregnancy yoga instructor near by and we swapped leaflets & business cards. I offered the instructor a discounted massage so she could see my room and try out a treatment, she loved it and recommends me to her yoga clients so I often have a steady influx of pregnant ladies.
When I first started out I did loyalty cards and offered a discount after 5 many treatments. I don't do them now but they were popular and helpful when I was trying to get people to return in the early days.
I have some loyal clients who dread me being off i.e. on holiday or sick and have to go elsewhere. These are the most common complaints I've heard when they've visited someone else: the therapist was too formal / not friendly enough which in turns means that the client isn't relaxed, the experience felt rushed, treatment didn't start on time, outside noise, the therapist didn't focus on the areas that the client is having trouble with, cold room, cold towels, hot stones not warm enough, they were in pain afterwards (and weren't told that this can be normal), no ambiance, therapists didn't take card payments. No idea if any of those apply to you, but I always find it interesting to hear what people have to say about other places they have visited.