Slow-motion (12-15 seconds per rep) snatch pulls. Use this to really focus on your double-knee bend setting up a vertical second pull and a straight-up-and-down triple extension at the end.
Snatch pulls full speed while focusing on driving the bar straight up and not off your pelvis. If the bar is pushing forward, you're still doing something that is causing the bar to bang on the pelvic bone.
You might want to try other things to work on your snatch strength without risking your pelvic bone for a while, like snatch balances and OHS.