Maybe I was wrong about the power supply, although I think you can be pretty sure HC-12 doesn't need the full 200mA. The only thing that is notable in your pictures is that you are running off a USB cable, a long one, and presumably off the PC, from which you should expect no more than 500mA, and less from a laptop. This raises the possibility that you might indeed be a bit short of overall power, and using a 9v wall wart is a better option. Note though that Arduino tut shows HC-12's power is taken from Uno.
If you intend to get NRFs you should be aware that they normally have nowhere near the power of the HC-12. One module would need to be high power, with an external antenna.