Breastfeeding at 9 months

Hi mommas, would appreciate some feedback about breastfeeding! 

My son is 9 months old and has been exclusively breastfed. Over the past 2 months, I have tried to introduce solids (pureed sweet potato & breastmilk, mashed avocado, rice cereal & breastmilk, mashed banana & breastmilk) but aside from a tablespoon here and there, he won't eat. He is also a very active boy, and spends all day crawling, pulling up and cruising--and less time at each feeding. I figure he is also burning more calories, and needs more to eat. 

Since the day he was born, he has breastfed every 2-3 hours around the clock (day & NIGHT). I also pump several times a day to increase my milk supply (I use the extra milk to mix with his rice cereal and veg). He has always gained weight well, but between 7 - 9 months, he has only gained 1 oz/week. This has totally stressed me out. Since I found this out a few days ago, I have been giving him an extra 4 oz of pumped milk a day, but don't know how long I could keep it up. After 9 months of no solid sleep, I think the exhaustion is taking a toll on my milk supply too. I am also concerned that he needs consolidated sleep but can't get it because he is hungry at night. I am not sure what to do! Any advice would be greatly appreciated.

p.s. the extent of my pediatrician's helpfulness consists of giving me a gerber company handout