Private health cover doesn't cover anything that is not in a hospital, so none of the general ob fees before the birth are covered.

The medicare safety net only includes your out of pocket expenses, so maybe you are over estimating by including the total of the bills from the ob so far?
I found that it was the management fee that put me past the safety net limit so we only got the 80% back for about half of the management fee that was past the limit. I hope that made sense.