If it was an appointment made for your daughter then they shouldn't really be bringing up your weight whilst your there. You know how tough they are when you want to ask them something when it's your kids appointment, they won't let you as there so pressed for time.
Don't let him get you down, you've already started going down the right path and when you do go back you can surprise him by showing all the great progress you've made.
I do think it's a bit much saying go back in 2 weeks though, how much does he expect you to lose in that time!? I would say going back in a month would make more scense, but then hey i'm not a doctor