Setting up a focus group

Elementary teachers and early childhood educators are my target market. But I am having trouble connecting with them. I want to set up a focus group to understand their needs/get feedback. How do I got about doing that? I emailed existing customers but they only came back with positive feedback. I would like to hear from people who haven't bought from me. How do I find people? Who do I reach out to? And honestly, why would they spend their precious time giving me feedback?

Thanks a lot for your time!