Hi My 4 month old seems to be drinking less m...

Hi My 4 month old seems to be drinking less milk. He is having only formula and takes from 80ml to 120ml. He is 6 kg in weight and was born 5lb 8oz. At around 3 months he was having about 180ml. Is this because he was going through a growth spurt. I have been told ( by my mum) to start him on solids, and alot of other people have said not too. I'm not sure what to do. As the saying goes (mum knows best), so do I listen to my mums adivce or people from child and youth health. I can't feel any teeth and I'm not sure if this may be causing him to eat less. He also cat naps throught the day, sometimes I give him a top up bottle, and just today it was 7 hours between feeds and he only eat 120mls. He always seems content and happy, but now and then has a grizzly day. But overall he is a good baby. Any suggestions why he may be eating less He's calling , got to go All the best