Metabolism vs back problems = not losing it

Right, here goes. I have been the queen of dieting since I was a kid (my mum had me permanently on a diet from a very tender age). I have lost, gained, lost, gained and am fighting what seems like a losing battle. I was very active as a kid, sports, ballet and never kept still and was raised on fresh veg and road kill (my dad was a HGV driver and brought home his casualties). BUT, I was always solid, slightly chunky, muscley but with a light covering of fat. No matter how much exercise, I could and don't never lose that fat. I am at a difficut stage now where I have been diagnosed with 2 bulging discs in my back (where else?) and cannot do hard impact exercise as this affects my hips and walking but I do play table tennis for half an hour a day and swim twice a week. What with doing my utmost to stick to the 1200 calories a day, I am finding it hard to eat that much without resorting to a takeaway curry or a doughnut just to top up my intake which will soon get rid of the calories - slight exaggeration but you know what I mean! After 4 weeks of calorie counting, checking I am getting the nutrients I require, doing exercise that I can physically cope with I have only lost 2 lbs and to be honest, my scales aren't that clear and had to take a bit of a guess at that. Now, I don't want to sound like a sickly runt but eating too much fruit irritates my bowel too much and I can't bear the pain associated with that so I avoid it. I love salads and veg. The one thing though that keeps me going are those lovely carbs. Without the carbs I am hungry soon after a meal without any in, I get cold to the core, even in summer and cannot do without them but thats where the calories lie. My metabolism is shot and always has been but mentally I am finding it all too emotionally consuming. With all of this however, I am determined to lose weight, again, have every intention to, again but have body issues that are impeding me. Help me obi one......