At this age, the basic day's events of just eating and staring at mom are exhausting for a lo. And while they seemed to have plenty of rest during the day, they are still pooped out by the evening. Plus, most mom's supply is lower in the evening, thus causing the need for more frequent feeds. If on a 3 hr routine during the day, it is common at this age to feed every 2 hrs in the evening. However, also watch for the possibility that he just wants to suckle something to calm down.
I think you're both doing great!