A lot of mothers actually dream of the spirit of their child hanging around before birth. Some who remember the time before and during infancy say they aren't always physically in their body even after birth, and they choose to wait for the body to develop before entering full time. It's possible that your baby's spirit spent time close to you even in the hospital, and it's very likely that he hung out with you for months or even years before he was born and "chose" you for this brief life experience even though he may have known he wouldn't be able to stay very long this time.
You may even have shared other lives and relationships with each other in the past.
On a spiritual level, you really can't lose anyone. The spiritual connections that link us aren't visible here, and we often don't notice them unless some unusual event helps us to realize there is more history between souls than we remember in every relationship. The relationships often already exist on some level, and we just add new aspects to them in each life. In fact, you have a whole network of previous live's family, friends, and spiritual guides who deeply love both you and your son on the other side. Right now he is more spirit than infant.
All this to say, don't worry that he won't know you.
It's perfectly normal to miss him. Just remember you are not alone, and he is not alone.
Take a moment and think to yourself that he is right next to you, snuggled close and trying to help comfort you. That thought is an event that a great many intuitives, adults, and children who remember (or connect to) the space between lives say is true and real. If those people comforted those they love when they moved on, then I think it's safe to believe your son knows you and is happy to visit you even now. You may not sense his presence directly, but you won't harm anyone if you believe this is true. I hope it helps a little.