Could it be a growth spurt?
How can you tell if you have a hungry baby? Unfortunately there is no hard and fast rule but generally hungry babies tend to cry for a feed more often and will feed longer when you do offer them their milk.
At around six weeks of age, many babies go through a growth spurt which can mean a hungrier baby for a few days. While it might seem like the feeding routine you had worked so hard to establish may have just gone out the window, it's worth bearing in mind that this may occur randomly so you can just increase the frequency or amount of the feed and then allow the pattern to settle back after a few days.
Too early to introduce complementary foods (solids)
Lots of mums wonder whether a hungry baby means that it's time to start introducing solids. However, this should only happen around six months. Your baby's insides are not developmentally ready for complementary foods before four months and introduction to solids prior to this should be avoided. You can be confident that breast milk or infant formula will give your baby all of the energy and nutrients they need.
Some babies aren't as hungry as they seem
Some babies also like to suck for comfort and seem to be demanding milk when actually a cuddle or some other response would work just as well.