I know the feeling. I think calorie counting might be good for you. You can get apps on your phone to count for you (rather than adding them up in your head and writing them down). I use myfitnesspal, which is really good. I'm on a 1200 calorie diet, I do go over sometimes but never over 1500. You always need a calorie deficit to lose weight. Up the amount of exercise you do if you can (I have a very physically active job so that's how I get mine in). As for getting hungry, carry healthy snacks around with you. I usually have an apple in my bag in case I get hungry and drink loads of water throughout the day. Your brain can sometimes mistake hunger pains for being thirsty.
If you have a moment of weakness just think of the future, a slimmer and healthier you, and you'll soon start to put down that bar of chocolate and packet of crisps. And if you do fall of the wagon for a day...just jump straight back on, don't punish yourself!
Good luck! I hope I helped a bit