Anyone with older kids panicking?

I am now pregnant with #3. My two other children are 12 (almost 13) and 7. I know I've done this all before but I can't help but panic a little. I'm really doing this all over again? Diapers, feelings, potty training. I'm so extremely happy that I'm having another baby but a part of me is like WOW. Am I alone feeling like this?