Feeding Problems???

My kid's feeding pattern has changed a lot for the past week and it's making me worried. He is 11 weeks old😌😌

He used to eat 4-5oz every 3 hrs and a long stretch during the night (8 hrs max). He would eat total of 30-32 ounces a day.

Recently, he would only eat 3-4 ounces every 4hrs and rarely 5oz. He would only eat total of 24-28oz a day now.

I guess, I was expecting him to last longer stretches but expecting him to eat more ounces. He just seemed to last longer between feedings but has been eating the same amount or less even.

My MIL also pointed out that he arches his back when she fed him but I rarely noticed that at home and when he does it, it's usually when he does not want anymore of his bottle and he does not have any other colic symptoms.

Is this normal? We still have at least 7 wet diapers and poops once a day pr every other day.

Any thoughts and advices?