I'm having those feelings but I had the same feelings when ttc #2. Just reminding myself that we got through everything well with #2 (except the sleep issues!) and I will be so happy to have #3, too! I am so excited to see what the new dynamic with three kids will be, especially since we're trying to have the next one soon (there was a 5 year gap between 1&2; looking at a 2 year gap this time). I am extremely excited to have kids close in age that will (hopefully) play together. I know my oldest is a bit too okd to really have that, but he was happy being the only one for quite some time and now we will kind of get to experience both having an only child and a couple kids close in age (in theory).
Sorry got on a rant!