Modifying a buck converter for lower current rating
You might be better off choosing an IC that is targeted at providing the level of current you're looking for. I haven't looked at this design in detail but it is normal to select an inductor value that results in a peak to peak ripple current of about one third the output current, so the inducance value will be higher. Inductor needs to be rated for peak current. Smaller diode sounds OK. You can no doubt tolerate less capacitance at the output. All these changes will no doubt impact stability. I suggest you systematically work your way through the datasheet design process.