My baby is 7 months old.he weighs around 6.2kg.he is underweight .but he is very active for his age.he still?

Spits sometimes.his schedule is like this:6am breastfeed ,wakeup 7am,bf around 8 am.nap around 9-10 am.bf and solids like fruits,play bf and nap around 12-1 pm.wake have lunch ,play nap for 2 hrs.wake up around 5 pm bf and play ,bf and nap around 7 pm.wake up at 8pm have dinner at 8:30.bf and sleep at 10 pm.bf 2-3 times in the night.I am confused when I should bf and when I shd give him solids and how much can a7 month old eat .he start his. Solids at 4 months.he needs to gain weight also I have tried giving him him variety of food but he is not gaining much weight .I am worried.can some one help me out with the feeding schedule for my baby.when shd I bf and when shd I give him solids .