Monitor Your Baby's Weight
A good sign of baby getting enough milk is weight gain.  Babies will lose a bit of weight in their first few days of birth then starts to gain weight typically by day 4.  Babies will gain their weight back by the time they are about 2-3 weeks old.
Check for Wet and Poopy Diapers
A sign your baby is feeding well is that by day 5-7, they are having 6 or more wet diapers in 24 hours and are pooing often (average 3 times per day).
Developmental Milestones
As your baby grows, they will experience many changes and development which may affect when and how often your baby wants to breastfeeding.  These milestones include gaining more awareness (more distracted during feeding) around 4 months, teething, and starting to crawl. It is important to follow baby's cues on when and how long to feed.