My boy is 13 months old. He has 3 solid meals and 3 bottles every day.
Sleep: 3 hours during day time (two naps, each about 1.5 hours) and 11 hours at night (730-630am).
His sleeping routine has been like this since he was 9 months old.
Sayuri Li, my baby had 5 bottles and 1 solid meal when he was 6 months old. Well... every baby is different. Still, it looks like your baby is having too little formula as a 6-month baby.