What you should do is cut down the size of your meal and eat more times during the day. Eat a small breakfast of something quick and easy to eat (I've heard overnight oats are kinda cool, like you make them the night before and you can make really tasty combos and you don't have to do the work in the morning! Or make up some fruit salads and mix them with yoghurt or something), eat a smallish lunch and an average sized dinner. I do this and I am 5ft 2 and just under 8 stone. I don't exercise that much, I don't have 'skinny genes' at all, like I haven't been running over the winter so my only exercise has been a friend's aerobics class every wednesday. Try not to snack and if you do make sure it is something as low calorie as possible.
Also something that massively helped me is my water intake, try to drink 2 litres of fluid a day, be it water or tea (not coke or lemonade or anything) and it actually fills your stomach and you feel so much better in general. You can try to exercise but it's not as essential as sorting out your diet