I can't think of much better advice than to start to turn up the heat a little on the lifestyle changes (low calories, more exercise, cutting out processed foods) and aim to wean yourself gradually off insulin.
Because you're on insulin, you'll need to be careful of hypos and make sure you don't risk going too low if you do step up the lifestyle changes. I'd say "if in doubt inject slightly too little insulin rather than risking too much" but anything affecting insulin doses (including any change to lifestyle) is really best discussed with the doctor.