just how much voltage do you intend to produce with your switcher? my opinion is your choice of fet is not suited for this application.
pick a vendor (fairchild, st, irf), and then browse their application catalog for switch-mode power supply transistors. the bss123 has a current rating of 170mA at 100v, I'd go for something rated 3 or more amps at 30v or less.
gate voltage is not as big an issue with mosfets, gate current is. voltage is a bjt requirement. your driver needs to source sufficient current to quickly charge and discharge the gate capacitor inside the fet. Most fets specify a rated voltage "Vgs" ... good switches are 2.8v, acceptable is 4.5v, anything above that will need more voltage, hence a special drive circuit (like a charge pump).