2 year check-up

Ali had her 2 year check-up today. She is 24lbs and 34 in. Those are the same stats as when she was 18 months.  Developmentally she is right on track. I am concerned about the fact that Ali has lost 2 lbs in the last 3 weeks. The JRA can cause growth restrictions so I am wondering if that is what is going on. Her doctor said he would like to do a weight and height measurement when I have the baby in a couple weeks and bring him in.