Oh OP, I remember it so well.
My first, ate, slept, smiled for a bit for and then went back to sleep.
He was a super easy baby.
Suddenly at 4 months he didn't want to.go back to sleep.....he wanted entertaining.
It was one of the biggest shocks and took huge getting used to.
At times I found the days very long.
I ģot into the habit of going out...long walks...baby groups.....but it was tedious at times..
It was a huge adjustment and at times, very very lonely.
I didn't have friends with babies either.
I really wanted to stay at home and mind him myself, but during those early days nearly cracked and return to work.
Do not be hard on yourself....it can be a huge transition for some...it definitely was for me.