Oh dear. I am going to be drawn into this. I tried to distance myself and it did not work
Firstly, the LM317T is bang on for the job.
Secondly, I believe the 10mm LEDS are just that. 10mm white LEDS that use only 20mA per LED. Total of 12x20Ma= 140Ma. Still good. No need for a BD of any sort. A little BC 337 can handle that for ever when saturated.
You see what is happening here once again. We are complicating simple things.
Just because we are bored
And also dealing with a circuit that is a non- starter anyway. Common guys. Don't do this to me.
Regards,
tvtech