If I have no alerts on my StingBox, am I guaranteed not to have been be hacked?

No, StingBox is a honeypot, not a 100% guarantee you have not been hacked. If an attacker stays on a single host on your network it is likely that StingBox will not detect the attacker (however, we may have detected the attacker when they were trying to compromise that first host). We suggest having endpoint security for the devices on your network in addition to the StingBox.