Oh Ally, I want to give you a big hug!!
First of all, while you are technically overweight- you are NOT obese, so get that out of your head. To get within a 'healthy' weight range for your height you would need to get under 10st 10lb- a loss of just over a stone, which is NOT a huge amount in the grand scheme of things? To put it into perspective for you- at 19 I was 5ft2", 17 1/2st and morbidly obese- i.e. I was in danger of dying from my weight!
Now, thats the mini-lecture over (I hope I didn't offend you?!). You say you've tried diets and calorie counting before? I hope I'm not being presumptious, but my guess is they were 'faddy' diets and you were restricting your cals as much as you could? I'm assuming this because you say yourself these times only led to massive binges, which to me says you were really denying your body of nutrients and the reaction was to crave the foods you were restricting? Please correct me if I'm wrong?
After 30+yrs of 'dieting' I'm only now realising you don't need to starve yourself, or eat certain foods to lose weight. It's pretty simple math- If you use (burn) more calories than you eat then you'll lose weight. But- theres a snag- you need a certain amount of calories a day for your body to function properly. If you google BMR Calculator it'll tell you how many calories you need each day. If you don't do much exercise, and are pretty much a couch potato, then multiply that number by 1.2 to find out how much you burn/use each day. Thats all a bit technical though.
To lose weight it depends on what you want to do? Do you just want to make better food choices, or calorie count?
As you have so little to lose I'd say by making a few small changes you could lose quite quickly without really trying, if that makes sense?
Cut out takeaways/processed foods (ready meals, packets etc.), try to eat as 'fresh' as possible- especially with meat/fish?, avoid sauces & gravies unless you know they're low-fat, use herbs & spices to flavour your foods, (obviously) avoid crisps/choc/biscuits or at least swap them for healthier alternatives like oat/rice cakes, treat-size bars (no mor than 1 a day though!) or low-fat biscuits. Try to get a little exercise at least once a day (30min walk is the recommended amount?)
Try not to compare yourself to your friends? I know it's not easy, especially when you're all out clubbing or shopping together, but try to accept that everyone has a size for them- and who knows- they could be skinny but miserable because they never allow themselves to relax around food? It's not the enemy, a little of something never made anyone fat, it's about learning when to eat what you want, and what it is that you're eating?
Sorry if I waffled a bit? I hope I helped a little? I'm not sure which way you want to go so I tried to cover all bases?