J20, I have an 8 yr old DD. She is a very bog girl too. She is 1m38 tall and a susbstantial weight, despite our very healthy eating approach - often in age 10+ clothes. All her life she has worn 1-2 yrs above her age, when born she was so tall she had to wear mothercare 3 month stuff.
My DD is also a bit cheeky and likes to get the last word in - drives me bananas.
I genuinely feel you need to see your GP about some help with your relationship - I did, and, although we haven't yet been to the positve parenting place I have read up on some better parenting techniques.
I have a 4 yr old DS with severe special needs and a DH that works away a lot, meaning she doesn't/didn't get as much attention as she needed.
She has said she hates him because he takes up my time and that things were better before he was born .
I wouldn't stop her having cake, tbh. I think banning her from eating certain things can actually make her want them more and lead to a lifetime of a very poor relationship with food. We just don't have biscuits etc in the house, we bake together and make small batches of biscuits. We still have chocs and easter eggs as we hardly ever eat them, maybe once a week?
I have taken her to see 2 diff GPs (at 5yr and 7yrs) as my DH is obsessed by her weight (which I am trying to protect her from) I spoke to them both beforehand, so as not to discuss it in front of DD, and told of DH's fear. Both GPs told me she 'looked like a normal little girl'.
They also said although she didn't need to lose weight, I should try and keep her weight stable. She now weighs about the same as she did August 2007 - all the cross country running at school seems to be paying off! We are a very active family (we have ponies and spend much time outside) but have built more activities into the weekends we go to a local wood and have a lovely long walk inc a bit of tree climbing, camp building.
I now make much more time for her, doing things she wants to do - even if it is hard with DS. I love spending time with her now, and a while ago I didn't, I didn't even like her very much sometimes - our relationship is so much better than it was.
If you want to CAT me feel free, it is hard for me to discuss this in public, so I expect it is the same for you.