Don't worry ya. My baby still drink 125ml when she was 1 year old.
Now she is 16 months and drink around 160ml and weigh around 9kg.
As long the output is good, it's fine
A four-month baby should be around 7.0 kg if the baby is a boy and 6.4 kg if the baby is a girl. check whether your baby has age-appropriate weight,