How much weight do you reckon i could lose a week??

if i drink 2 litrs of water a day & if ieat healthy foods eg bran flakes for brek, piece of fruit , fish & veg for dinner ,then another piece of fruit,then for tea say chicken & veg! but on another day say salad for dinner,ect.. stuff like egg whites but no like starchy foods. how much do you reckon i could lose over 3 months ? and im completly cutting out fatyfoods like crips choclate ect and im only gonna drinkwater! i weigh 12stone and i want to lose about 2 stone!