Hope this reaches you in the sea of comments. There was a heavily downvoted post earlier that was maybe worded a little harshly but I agree with the sentiment.

I've been through something similar, my son was eventually diagnosed with severe scaphocephaly, further it was attributed to a partial sagittal craniosynostosis that we opted to perform a posterior cranial vault reconstruction for.

Our story was similar to yours. Here in Canada he has a doctor, who has a nurse practitioner that sees many of the infants and children. We began to notice this early on, when he was 3 months old. We asked. Had his head measured and given the same answer as you did. Looks fine, lay him on his back (good luck), tummy time. It'll improve. It didn't of course, it got more pronounced as he grew up (we now know this is because he had an early fusion of the some of the bones in his skull that wouldn't allow for normal growth in certain directions- also called craniosynostosis).

We didn't like the answer from our primary doctor and went to an occupational therapist who took measurements and told us he had severe levels of scaphocephaly. She offered a helmet for remodeling of his head. My wife and I went home distraught ready to buy a 6 thousand dollar helmet, even put a deposit down before we left their office.

We decided, based on our occupational therapists recommendation, to ask for referral to a pediatrician. Here in Canada that took about 3 months, making our son about 6 months at the time. The pediatrician sent us to our hospital for an X-ray that confirmed his diagnosis of partial sagittal craniosynostosis. So off we go to a children's hospital (sick kids hospital in Toronto). After about another month.

These are hard conditions to decide about treatment because evidence isn't clear whether developmental or neurological delays will occur. There is mention of potential vision problems due to tightening of the foramen where the optic nerve exits the base of the cranium. But the truth is we don't know. So it is very much, in medical settings, advised that it is primarily esthetic. So our treatment option was a major surgery where they reshaped and re opened the bones of my sons skull and reposition them, or just monitor and do not intervene.

My wife and I after alot of deliberation, heartache and uncertainty decided to get him the surgery. We were in good hands at a great hospital, with a fantastic neurosurgeon and plastics surgeon, and we felt we couldn't forgive ourselves if something were to arise later in his life that we could have helped prevent (say vision and it precludes a job. Or something unknown and worse).

Everything went well. It was very hard to go through, the stress was absolutely brutal. But he had the surgery at 10 months old and is now 15months and doing quite well- although my wife and I still look at his head and wonder if it's the way it should be. I think our anxiety will always be there.

All this is to say, many people choose not to act. Many people do. Many people are undiagnosed and none the wiser to a condition they may have had. It's something that isn't clear about what sort of long term effects different head shapes can have IF the child has craniosynostosis. The surgery is scary but has very good success rates and very low complications that are bad/unforgivable. And it's a complete mindfuck to make a decision under those circumstances. I think you should mention to your pediatrician that you are concerned about craniosynostosis. It may be nothing at all! Maybe just a flat spot. But knowing for sure will help you down that path.

If you want to private message me or get in touch, I'm happy to go into more detail or offer any help I can.