Im a female and i weigh 217 and i've just started doing crunches but i don't want a bulky tummy i want it flatten..will crunches flatten or bulk me up?

Abdominals: Crunches will do neither. Crunches are exercises to help strengthen those respective muscles. Flattening your stomach is due to reduction of body fat and bulky abdominals are due to muscle growth. Women have 1/16th the testosterone of men & most men can't build abs, so, don't worry about bulky abs. Eat less calories, higher protein, & blend of weights & cardio training to reduce bodyfat.