start keeping a food diary, they will probably want you to do one so they can see what you're eating, when, how much etc. MyFitnessPal is really good, it tracks your exercise, too.
eating healthily is more than just food choices, it's about portion control, too. portion sizes that people are used to these days are rather bigger than back in the post-war rationing days and you can see that if you just compare the sizes of dinner plates from then and now. austerity hasn't yet affected people's plates, but perhaps it ought to. you can eat less without "going hungry".
low-calorie doesn't have to mean a tiny dinner either - sub sweet potato mash for white potato mash, use quorn sausages instead of pork, and add a heap of petit pois to the mash before pouring on 70ml gravy - you're looking around 400 cals and it's a bloody decent sized meal.
try not to be nervous at the dietician's, and take notes if you can. it's amazing what you forget afterwards and it's not from lack of paying attention, there's usually just a lot to take in.
good luck hun xxx
