It is best in the early weeks to feed baby directly from breasts rather than EBM as babies are very efficient and extract more milk from the breasts than any hospital grade pump. This will also help in establishing your supply if you are demand feeding. The best way to increase supply is feed feed feed around the clock, offering baby milk whenever possible. Newborn babies need to feed every 1-2 hours if breastfed.
If there is no need to pump, put it aside and direct latch as much as possible. Even 5 minutes it good for stimulating the breasts into making more milk. If you do want to pump to increase supply, it is best to pump in between feeds rather than to replace a feed.
Also, how do you know if your baby is not getting enough? The major sign would be wet nappies. If baby is having more than 6 wet nappies a day it is a clear indication that your baby is getting enough milk, after all, what goes in must come out! Please dont't judge your supply by baby's unsettledness as young babies will cry....A LOT!! They are still getting used to the new world around them as well as all the new and uncomfortable sensations of their body working on it's own.
All the very best!! It does get easier once you get the hang of it!