9 Month Appointment

So here are Callie's stats for her 9 month appointment. She is 27in long which puts her in the 25th percentile. She made it up the the 3 percentile for her head circumfrance but for her weight she not even close to the curve. She is definately about the 1 percentile. She only weighed 13.5 lbs. I am now really trying to bulk her up. I buy the baby food with the most calories and her doctor even suggested adding a little bit of butter to her vegetables. He also mentioned that if she does not start putting on weight by the time she is a year then he would consider putting her on a feeding tube. That would be horrible since she is now old enough to notice it and would be pulling it out all of the time. Let me know if you have any good suggestions.