My 10 month old is still on 5 bottles a day for a total of 35 ounces of formula a day.

His pediatrician said he should only be on 3 bottles a day now. He is only in the 7th percentile for weight and is a very active boy. He eats solid food at breakfast, lunch, and dinner. I can't imagine having him off 5 bottles and all formula when he turns 12 months. We tried dropping to 4 bottles and he was very cranky and wouldn't sleep or nap well at all. Wondering if others have been in this position. What did you do? What solids foods did you offer? How do I get him on less bottles?