Do you keep a food diary? I used to do Rosemary Conley and realised I wasn't losing too well, started writing down every single last thing I ate or drank (that wasn't just plain water!) supprising how much it adds up! I still do it, well right now on a VLCD so no unauthorised food but up till now I'd log every single crisp, grape, raisin!
I'd really really recommend foodfocus.co.uk. Log your weight & height, how much you want to lose (has a max of 2lb per week, so no good for me now!) then log all the food you eat in it! Produces a little graph and you can go, hmm, I eat way too much carb at breakfast or whatever. and you can 'offset' your exercise cals so it still tells you what to aim for cal-wise.
Hope that helps........