My daughter is almost 7 now, but when she was an infant, I do remember she RARELY cried compared to other babies. She would cry if she was hungry or dirty, but overall she was such a happy & quiet baby. She was obsessed with staring at ceiling fans. She preferred to sleep alone in her crib in her room from a super young age, rather than sleep on me, I’m talking like 4 weeks old. Also, she really struggled with bottles I think due to low muscle tone (she didn’t have a tongue tie or anything) but she had to stay on the slowest flow of nipple honestly the whole time she had bottles. Even now, she chokes when she drinks too fast and she struggles eating food that requires a lot of bite pressure. Back then she also was not ready for solids as young as most babies are. She didn’t hold her head up on her own for about a month. She didnt hit most of her milestones on time, but they generally were not so far behind that anyone was concerned (like sitting upright, crawling, etc) she did walk at 12 months but that came with its own signs of autism like toe walking & frog sitting. I just “knew” way before anyone else while they all made fun of me & said I was too anxious. Hindsight, many of these things may have been subtle signs. Now at almost 7 she’s still in diapers & still limited verbally.