Has anyone else ever felt like this before?

I have a 4 mth old son and I do miss being pregnant but I don't wish it on an everyday basis that I will soon. But whenever I went up to my OB clinic to get my birth control pills I seen all the pregnant women and it made me miss all those days coming to the OB and hearing the babies heartbeat and seeing him on the ultrasound machine. I love love LOVE having him here for me to hold and play with and just love but I miss those pregnant days just a little bit lol. Is this normal? Don't worry I am not going to act on it on the behalf that we can't afford another baby right now or do we have the time we were talking maybe in about another 2 to 3 years to have another one God willing.