Hi,
I wouldnt worry about those Schottky diodes as much as the ones on the uC chip. If that particular uC chip has protective clamp diodes, those might conduct before the external ones do and thus might have to take the bulk of the current. It's much better to use a current limiting resistor from the output of the second op amp stage to the diodes. You'll also want to double check the max output current when the output goes negative as that will be worst case power dissipation, which will be 12 times whatever current it can output. If the power dissipation for the op amp chip goes too high it will burn up.
Another added advantage to using a current limiting resistor is that it will isolate the output of the op amp from the clamps, which means the op amp will stay in the linear mode at all times. With the clamp diodes connected directly to the output the output will not always have a chance to keep the op amp in the linear mode and that could cause some unusual problems too, so a well chosen current limit resistor is very wise.