Hi I've gotten a lot of conflicting advice reg...

Hi I've gotten a lot of conflicting advice regarding solids, have been told that up to 9 months should be getting most nutrition still from formula or breastmilk but then have read elsewhere that by 8-9 months most nutrition is coming from solids. Which one is true? Have also read that by now should be on three bottles per day but what does that mean for volume? Is it supposed to be around 600mls per day? I'm worried she's not getting enough nutrients from solids as will only sometimes take her dinner (usually eats breakfast & lunch ok).