Babies sleep more. But a vet visit is a must,! Just to be sure. Also a young one like this may regress, and might need some comfort hand feeding. Offering some warmer oatmeal, or scrambled eggs before bedtime might be good. Also getting a digital kitchen scale and start tracking weights, a great thing to do for life, as can help identify health issues early.
Welcomed to the forum, congratulations on your new baby!