NO going back now... :)
9 months is a long time, you have plenty of time to mentally prepare for your new addition. It's okay to feel shocked and scared now.
I am 3 weeks away from delivering #3 and I have gone all around the spectrum with my doubts/fears/expectations too.
Actually, with each of my 3 (planned) pregnancies, I have had that "yikes" feeling upon finding out. Like, the reality hits. There's no turning back. Disbelief that it actually happened "so quickly". Plus there are weirdo hormonal things that happen to affect your feelings throughout the whole pregnancy.
And you can enjoy your first pregnancy in a state of bliss, because you don't exactly know what's coming. The second one I enjoyed in a state of overconfidence of thinking I was an old pro. Third time going in I think we have our eyes WIDE open as to what EXACTLY we are in for, which adds more fear, trepidation, anxiety.
You sound normal to me. You'll be fine :)
ETA: Suz T, God's plan to eat the zebra popcornopolis!!!! You crack me up!