You've posted yourself or your agency everywhere. You get tons of interest from job boards or other referrals, but they either aren't relevant or they stop communicating.
Here's the thing:
The big sites are full of recruiters and others who spam everyone, whether their gig matches your skills and requirements or not. The big sites don't care because they make money from the useless messages.
Hire an App Developer is specific. We don't make money on messages or to see listings.