is it too much for a 3 weeks old baby having 880ml formula milk a day?

Make sure no vomit. Ensure your baby is properly burped EVERYTIME after milk intake. You need to learn how to do it and be patient. Do not shake the baby like throwing them up and down to make them giggle. This can induce vomit later. If possible stay late about 1 to 2 hours the baby has slept to check they don't vomit in their sleep or breathing obstructed. And do not delegate this task to maid. From time to time they have sort of like spurt growth which has spurt demand for milk intake. You just go with what you baby needs.

How old is he? As they grow up and becomes more active, their milk intake increases. If concerned, check with pd if okay to gradually start solid food like porridge, fruit n vegetable puree. All the best!

That's quite alot. As long as he is drinking well and no vomiting then it's totally fine. Can just feed..

its normal for me

It’s normal.