Regrets...feeling guilty.

I have had this nagging feeling of guilt and regret lately. I know I should not dwell on the past, but I just keep thinking that I missed something in Logan's first 7 or 8 months of life. I wish I could have counted on Logan's doctors to find it, but I know his ped just doesn't have the experience. I told him at several appointments early on in Logan's life that I thought he was sleeping too much. My concerns were always answered by "babies are supposed to sleep a lot". I feel like maybe, if I would have searched harder for answers, Logan maybe would have been able to start developing sooner. He basically slept his first 8 months of life and just in the last couple of months started changing and learning. Before 8 months he had no motivation in him to do anything, but suck his thumb. For a while I was very worried that he wouldn't snap out of it. He didn't smile or respond to his name. Finally, at 8 months we looked into his hearing, breathing and chronic cough problems, but I feel like I took action on those things too late. But how was I supposed to know that he could have sleep apnea as a baby, and I am just learning now about other problems that babies with DS can have. Why didn't the doctors suggest a sleep study or looking at his airway?? Now, I have been made aware that DS children often need swallow studies to make sure they are not aspirating into their lungs when they drink. Could this have been happening to Logan since he was born without us being aware of it?? Could it have caused his chronic cough and noisy breathing. Was he getting enough oxygen when he was sleeping before we put him in his car seat to sleep??
I have to find a way to put all of this behind me and out of my brain. He is doing so much better now, but I just wonder if I could have found a way to make a difference for him back then.