With a boost converter, there is a point where increasing the duty cycle does not increase output, but reduces it.
Tips:
For a 3.3uH inductor, try a frequency of 400k.
Expect current waveforms to peak as high as 5A.
The first half of the cycle (the power input part of the cycle) should have very little parasitic resistance. It should be less than 1/20 ohm.
Your smoothing (output) capacitor must endure several Amperes going back and forth through it.
Also consider making twin interleaved boost converters.