I have predicament, I am putting up a shelf into the wall.

The wall is plaster, and then hollow and then concrete. I have screws with toggle bolts on them.

The 2 inch screw with the toggle bolt was too short to get the toggle bolt inside the plaster to the hollow part.

The 3 inch screw with the toggle bolt is too long because it hits the concrete. But the toggle bolt will reach into the hollow part.

How do I approach this dilemma? Do I need to drill into the concrete somehow? I think my current drillbit is incorrect for doing this, but I'm not sure.

Insight appreciated