I think my daughter is a bit portly too! Same age as yours, but I have to say I aven't measured or weighed her since she was a baby.
I'm trying to offer her fruit/veg based snacks and keep her diet generally healthy. She adores food and will eat and eat given half the chance, and is really unpicky so I suppose we have to be grateful for that! The only reason I'm concerned at all is that DS1 was a bit plump from about 8-13 until he grew, and he was bullied a bit at school - nothing serious but it did upset him. They are quite similar in their eating habits, so I am trying to keep an eye on it without making a big deal of it. I actually think it's better to do nothing and have them a bit plump than go on and on and they end up with an eating disorder. Also would agree about milk - limit it to one drink a day,and not with meals, as long as they're getting calcium elsewhere.My son used to drink loads and will still drink a lot now, given half the chance.Perhaps cut up carrots, or put a dish of cut up fruit in the fridge, so she can still help herself?
The other thing I think you have to watch out for is portion size - are you giving her the same amount, or nearly, as you have? I know I tend to give my daughter too much because there are two adults, one 14 year old, one 12 year old who eat loads, so I just dollop hers out on the plate almost the same. I realised I do this because my ds2, who's 9, is not really interested in food so I give him small portions or he won't eat it - he seems to get overfaced very easily - funnily enough he is by far the slimmest of my children! I realised I was giving her far more than him, and she was eating it! So now I try to give her a bit less, and she hasn't noticed.
Also activity - my dd loves ballet, and also likes riding her scooter to school and going to the park and bike riding. My dd1 is very sporty and active although she eats loads and I think this is down mainly to activity levels.We do try to go for a walk most weekends too, or swimming if it's cold/wet.