Help please - Feeding query

[Grommit]

My 15 wk old is still feeding every 4 hrs but only takes between 4-6ozs. He is not gaining weight well. Should I put him on the heavier milk (SMA white) or even start on solids? Advice please...

My son has never liked milk, he's 7 months now and I started him on solids at 4 months because he didn't like milk and I was worried he wasn't getting enough nourishment. I still feed him milk at 7am, 11am, 3pm, 7pm, 11pm and the most he takes in a day is about 18oz but he has 3 meals a day and is putting on weight normally. I was just worried he wouldn't get enough fluid. I was giving him SMA Gold and changed to SMA Progress which is lighter and he seems to enjoy it more.