Sleep regression or what?

Arsh

So my LO is 14 weeks old that is 3.5m old and i believe he is going through the 4th month sleep regression but the signs are different. For instance, his feed has become very less, he’ll drink 2oz after every 2-3 hrs or so and sometimes even less than that. It happens that once in the day he’ll eat a lot like around 6-7oz and then the whole day he won’t even finish a 4oz bottle. He is very tired all the time but not fussy or cranky. He also doesn’t want to be held extra than before. He sleeps for 2hrs straight at night and then will wake up so i either put the feeder in his mouth and he’ll go back to sleep in 5 mins or rock him to sleep. But it doesn’t take more than 5-10 mins. I feel like he’s always sleepy. Did his routine check up a week ago and everyth is fine. He is not teething bc the gums aren’t swollen. And no thrush bc i just got it teated. Can it be the 4th month sleep regression?