Your design could not have worked.
The typical design is to put a serial resistor in with the leds. This resistor generates a voltage drop proportional to the current going through the leds. That signal is then compared with a preset threshold to determine if you shut down the switch or not.
This mode of regulation produces a (near) constant current that is irrelevant of the leds' forward voltage drop. And by changing the resistor, you can program the current going through the leds.
Your design does none of that.