I don't think that it's about how many are in your area, necessarily. I think that just means you need to be more assertive in advertising, and take the extra step in doing flyers, cards, etc.
When it comes to interviews, be as prepared as possible. Have your policies and procedures set up, have your paperwork ready, don't be vague about things. If parents are interviewing a number of people, you want to stick out as a professional and capable caregiver. Have your home completely set up the way it would be. When I first started interviewing, I didn't have things quite the way I wanted them (no baby area yet, etc). Parents don't care about "what I'm going to do", if the daycare across the street is ready to go!
I would sell all your best features like the ECE, and double check that your rates are on par with what is common in your city.
Find a part time income if you feel like you need it, but if this is what you want to do, then don't give up yet. It seems like all across Canada, there is the same trend: no luck for a period of time, and then bam! You fill right up...
Good luck