My son will be three at the end of March, just weighed in at 37 lbs but is also 38 inches tall. I know it is just my opinion, but she is just a baby still! When my son was turning two, he was at about 30 lbs, they really slow down during that second to third year as far as growth and gain because they become so much more active. Personally, I would try to limit milk, but then again my kids have never been big milk drinkers so perhaps that is easier said than done? Maybe switch to fat free milk and limit it to meals, if she is thirsty between meals, then water? I am a daycare provider for a little girl who just turned 2 in Dec and she, if given the opportunity, will ONLY drink milk, which then fills her up so she doesnt eat anything. When she is here I have switched to all open top cups, yes she does fine with them with the occassional spill, BUT it has drastically reduced the amount of milk she drinks AND she eats a lot better. She doesnt feel like it is being taken away becuase she still gets it, but it takes more time and more effort for her to get it than to just sip away on a sippy cup. When we go someplace where she will need something to drink, I will put water in a sippy.
I wouldn't worry about his weight but I would consider finding a new pediatrician, I think 2 years is too young to be labeled as overweight. Like someone else suggested, maybe some indoor swimming, more frequent trips to the park, a tumbling class, let her walk rather than ride in the stroller... she'll slim down with just a few small changes as this year she will become a lot more active, increase her gross motor skills and will become way too busy to eat and drink (thus taking away the sippy, she will have to be in one place to drink her milk!)