C.O.
Please don't freak out!!! Kids grow and lose weight and then gain weight. Over the summer - expect her to stay even if not lose or gain some - as most kids are VERY active in the summer.
I wouldn't worry about one pound. And if the Doctor's not worried - why should you?
Focus on her diet and getting her regular so that her bowels don't get messed up....I know how hard it is to "fix" the bowels once they get swollen from constipation....can you talk to a nutritionist to see what would be best for her and her body? Is it possible she has Crones or Celiac Disease and that is what is causing her constipation?
It's okay mama - breathe!! You are a good mama for paying attention!!! Don't freak. She'll be fine!!