So my brain has been seriously racking on questions on breastfeeding like oh my.

Question -#1 after pumping is there gunna be milk left for baby if they want to nurse right after pumping or is it gunna take time to build milk back up first?

Question -#2 and secondly I’m starting to pump cause even with nursing my daughter she usually nurses for 30 mins every 3-4 hrs like clock work but I usually wind up feeling full and feeling let downs shortly after her feedings til it’s time for her to nurse again so how long should I be pumping for everything I’ve seen says 30+ mins but I’ve only been doing it like 10 mins maybe 3 times a day.