Great news, keep going. You will probably also get a few more customers in the cul-de-sac over time as some who didn't answer the door see you working, and even some who said no thanks just cause they don't trust someone knocking on the door - I just started a new street, and a guy comes over who had said no when I knocked "how much do you charge mate" I said "I knocked 2 days ago, you said you didn't need anyone ?" "Ohh did you, sorry, yes I do need a cleaner" He had no idea it was me who knocked, just used to turning away door knockers.
It does sound like you may have priced a little low. When starting out in any business, lots of people tend to underprice because they are afraid of losing the custom, and only realise down the line that they've made a mistake. Don't be afraid of quoting what you think is a good income and a fair price for your service. You'll be suprised when they still say yes for a few quid more. Lots of people are willing to pay more than the cheapest guy in town to get a reliable and quality clean.
If you haven't underpriced, just ignore the above, but thought I'd add it as it's a mistake most of us make.