I think the CM's criticism must be taken as a positive thing - like every parent I'm sure you want the best for your DD.
I used to be rubbish at cooking but my goals are simple try and get the children eating as little processed food as possible make sure they get a wide variety of different coloured fruit and veg every day and something from each of the major food groups - ie unrefined carbs, protein and veggies. Whether she eats it is another matter but if you offer it she will get used to good food. I offered steamed broccoli every day and for eight months it remained for the most part untouched but now my DC love it and always chose it first.
I think you need some easy meal plans: Have you seen [www.fishfingersfortea.co.uk Fish Fingers For Tea Blog] It is good and Annabel Karmel has some really easy things that are quick and take no skill to prepare.
For breakfast porridge or weetabix is always good with plain yoguart and chopped fruit.
Popular snacks in our house include chopped fruit, oatcakes with Meridian Peanut butter it has no added salt or sugar, eggy bread, salad ie chopped peppers, cucumber and tomato.
Meals when we are short of time include: sardines on wholemeal toast with salad, omlettes just grate in carrot, courgette, onion, chopped peppers and tomoatoes and a little cheese but cheese is very salty. Roasted chicken drumsticks (you just shove them in the oven and serve with stead rice and vegetables). Chunky soup made with veggies, lentils and chicken. Dahl with tinned tomatoes, grated carrot and peppers on pasta etc. Steamed fish (4 mins in the microwave is also popular).
Try only offering water, I'm sure she will drink it just persevere she will get thirsty.
My DD wears lots of dresses because she hates waistbands and always takes off anything with a waistband so I put her in a bodysuit with tights underneath so she can't take them off and shortish dresses on top. If you are really wedded to dresses at least make sure they are soft stretchy cotton (H&M is good for these, I got some yesterday for £2.99).
Good luck.