Stretch out your fingers and hands/wrist etc prior, give it a good 2-4 minutes worth.
Then lighten up with the fingers/slap, turn the volume up, that's what that knob is for, not to turn down so you have pluck the bejessus out of the strings
Old habits are hard and when you try something new, it brings you back to the newbie level.
I'm messing with double thumbing and feel like a beginner(and truth be told, am one!)
Regards,
Tom