Help, losing mummy tummy!! What else should i be doing??

I have 3 kids (youngest is 5 months) and i have recently started working out and eating less calories, i would like to really tone up and lose my mummy tummy! I work out 30 minutes a day (hiit workouts) and i have 1200 calories a day. But i feel like im getting no where, what else should i be doing?

Basically im trying to burn alot more calories than im eating!