9 day old length of feeding decreasing

Bridget • Mama to 2 boys 13 months apart 💕
My son is 9 days old. My milk came in on his second day. By the time he was 5 days old or so he was eating every 2-3 hours for a good 45 minutes each time and always pulled off with milk visible around his lips and was content to sleep until the next feeding. Starting yesterday he will only eat for 15-20 minutes at a time and is almost never content enough to go to sleep afterwards, I'm pretty much feeding him constantly around the clock. I know newborns cluster feed, but the shortening of his feeds concerns me. He doesn't seem hungry to me, like genuinely hungry hungry, he seems like this is for comfort and not for food. I may be wrong, though. Is this normal cluster feeding? Do I need to worry about my milk production? I try so hard not to fall into the trap of "low supply" worries- but it's hard when his habits change like this. I can still pump my normal amount from each breast, and his dirty and wet diapers are on par.