Something missing?

I had my son on 4/24.. He is so perfect.. I love him so much... I can't help but feel since I've had him (not being pregnant anymore) that something is missing.. I feel like I didn't appreciate this pregnancy enough, and I should have because it was my last one.. Already have a daughter as well:) Even though hubby says we can have 1 more if we move into a bigger house, but I don't see that happening. I love being pregnant. I'm in no way experiencing post partum depression.. Just wondered if anyone else felt this way?