What a great service you are providing to your community.
Do you have an information pack about your service that can be used as a pitch.
If you do not have one then I would recommend creating one based around the benefit messages from those that have used your service. You Facebook stream has some awesome messages.
If so, have you considered reaching out to businesses that cater for young children.
Companies that make nappies, baby formula or clothing providers e.g Cotton On.
Corporate Social Responsibility is becoming a hot topic for businesses at the moment and aligning to your purpose would be pretty compelling.
I assume that you have reached out to Nikau Foundation and other mental health funding initiatives.
The only other consideration would be to reach out to those that have used the service to see if they have connections that could support in terms of funding.
I am happy to assist if you need more detail or help pulling it together. I am sure that the advisors will have connections into some of the business types mentioned.