Don't know how you got those values....................
Right Ok, In the simulation though, when I'm drawing 300mA, the RMS current on the transformers side is about 1.4A RMS. Which is more than 0.6A RMS.
Below is the simulation of your circuit with R6 set to 90Ω to give about a 300mA load.
The measured transformer current is 614mArms.
The output ripple voltage is because the voltage drop across the regulator is too small and it's falling out of regulation.