2 month old baby drinking less milk

Hi, my baby is currently at 9 weeks old and the total daily milk intake has been reduced quite a lot since 3 weeks ago. The baby was drinking 650ml - 700ml and currently that has brought down to 450ml - 500ml (Baby can rarely hit 500ml a day). Baby can only drink 60ml - 90ml at a time. At 2 month check up, PD told me that it’s hunger strike and is not concerning since the baby is growing and no sign of health issue as well. PD also advised me to dream feed the baby if I want to increase the daily milk intake to meet the minimum daily intake (weight is 5kg) but the baby does not drink when sleeping. When I tried to feed more often, baby refuses the bottle and cry very hard. I feed 6 - 7 times now on baby’s demand. I have tried three different brand’s bottle, tried bigger teats, and three different formula milk but the situation still remains the same. Is this normal and will the intake increase eventually? Did you do anything special to increase the milk intake? It would be great to hear your thoughts. Thank you!