How to increase and maintain voltage gain of DC DC converter with switching load, and choose the right capacitor and indcutor
With 12 volts, 220 uH and 31 kHz you can analyse the energy transferred per cycle. At 50% duty, the time period is 16.13 us and this allows the current in the inductor to ramp up to 880 mA. This current and 220 uH implies a stored energy of 85 uJ. Barring losses, this energy is transferred 31,000 times per second to the load and output capacitor.

This is a power delivery of 2.64 watts at a duty of 50%.

If the load is 2.2 kohm and you want 120 volts across it then it requires 6.55 watts. So clearly you need more like 80% duty to achieve your aims. But this relies on perfect components with minimal losses and that won't happen in reality.

It's likely you are pushed significantly over the 80% duty requirement and this starts to be bothersome for boost converters. I see you have 4 inductors in series/parallel so, maybe just use two in parallel to reduce the inductance to 110 uH and the current will ramp to 1760 mA at 50% duty. This will then store an energy of 170 uJ and deliver a power of 5.28 watts i.e. a significant step closer.

But you have to choose inductors that don't get close to saturation at this higher current.