It's completely normal! They were all yours & now you have to share bubba with the universe.
I felt the exact same way. I my baby is nearly 8 months old but I still feel that way sometimes
I remember feeling "empty" So to speak. I had shared and felt something growing inside me for so long, that it took awhile for it to feel normal to just be me again. I remember shaking my belly and thinking it just doesn't feel right anymore. Lol... Of course I loved finally having my baby in my arms, but there is that weird empty feeling that takes awhile to shake.