New to thumbpicks

[G-Money]

i think you're on the right track with filing the pick blade down. try raking back the shape till it looks like a dolphin fin, the slope-ier side facing the string. This way you can get the flesh of your thumb to contact the string on its release at the same time as the pick material. Adjusting the balance of flesh and pick gives you a lot of control over tone, volume and ability to up-stroke cleanly. ymmv....