Ftm help 😁

I have been successfully (?) Feeding my 6wk baby and decided I want to start collecting milk for when he says with grandparents.. I don't own a pump and I don't really want to dedicate myself to pumping, however can express milk with my hand, and my opposite breast leaks when I feed, my question is how much will he need?! And how do I go about collecting it (can I collect it over a day into the same container or seperate containers each feed - feeding every 2.5-3 hrs ATM. Thank you

(Pic from first feed)