Concerned about weight gain

My 15 month old dropped on her weight.  She has always been measuring small on the weight but she only gained 4 oz between her 12 month checkup and 15 month.  The doctor said I need to try to increase her calories but sometimes she eats really well and sometimes she isn't interested.  She has always had an issue drinking milk/formula.  In the morning she will drink 7-8 oz but in the afternoon she only drinks 4 oz and same in the evening.  She gets juice mixed with water at daycare in between milk and meals and usually drinks no more then half a cup of that.  She gets one container of baby prunes everyday otherwise she is constipated.  I am at a loss as I can't force her to drink.  She eats table food for all her meals and does well with things like Mac n cheese, pizza, soup, bean burritos.  Any suggestions?  Should I be concerned that her height is normal but weight is not? Developmentally she is fine, walking, playing, trying to talk etc.  She had a cold right before her checkup and wasn't eating well and prior to her 12 month checkup she had a stomach bug.  She had ear tubes put in at 7 months old bc she had ear infections every 3 weeks starting at 3 months old.

[Renee Radenberg]

Her weight is just below the 5th percentile and her weight was on 50th percentile for her age. It is great that you are giving her table food/finger foods. As a guideline for a 14-24 month old child should eat the following: Dairy 4 feedings a day –Milk or breast milk (4oz), cheese (½ oz), yogurt (½ cup), or cottage cheese (¼ cup). Starch 4 feedings a day – Cereal (¼ cup), pasta (¼ cup), rice (¼ cup), bread (½ slice), or crackers (2). Fruits & Vegetables 4 feedings a day – Fruits (including 100% juice limited to only 4-6ozs) & Vegetables (¼ cup). Protein source 2 feedings a day – Meat or fish (1oz), egg (1), or beans (¼ cup). She should eat 3 meals and have snacks between meals using the foods above to be spread out throughout the day. Suggest giving her a 'sippy cup' at meals/snacks and give her Pediasure, milkshakes (milk and ice cream blended), or yogurt smoothies (yogurt and ice cream blended) in place of milk/fluids at meals and snacks. You can add fruit to the shakes/smoothies for additional vitamins and minerals. Recommend giving her a daily children chewable multi-vitamin. Hoped this helped you.