I'd like to give my experience on what I went through.
6 months back I was given my very own class, and from what I saw from the class numbers initially, it was a decent class of about 20-25 members per week. The very first day I taught that class I taught it the usual way, with no prior introduction from the previous instructor. The numbers were the same initially, but it dropped to less than 15 by the next week, and it stayed that way for at least a month.
I began to talk to the friendlier members and I found out that it was a personality clash. Not my fault at all. So I made friends with the regulars, and they introduced more members to my class. And somehow it worked, because my class now has a healthy number of 25-30 per week. That's not too bad considering I can squeeze in a maximum number of 43 in that class for safety reasons.
What I'm trying to say is that you have to keep pushing on and not worry about class numbers too much, because if people like what you are doing they will naturally come to you. Just do your best and try to create personal connections with the members, because they can, and will most definitely, bring in their friends to your class if you have that special connection with them.
Hope things turn out for the best for you!