You're doing fine. It's completely normal.
I sign people up some return some find it too tough. And even though you can go through the try it with food conversation with them, few take you up on the offer.
In the early days when I got no shows I used to ring round and ask if everything was OK. But then I'd find that people got shirty with me and it felt like I was nagging and they said they'd ring me if they decided to carry on. So now when people don't show up, I don't chase.
Eventually what happens is that you sign up so many people and after a period of time you get people giving it another go. So you get repeat business that way. You also get to learn who is likely to just show up for a couple of weeks each year or twice a year and who is likely to stay the course.
There is a bit of a slow down at this time of year because of people being on holiday. Similar thing around Christmas. I have also personally found that the beginning of a year can be a bit slow because new people have to try things like slimming clubs first before they come to us almost as a last resort.