I read through it twice so far and I really didn't have an issue believing Edward loved Nessie. I had to laugh at the reaction Ed went through when Bella realized she was pregnant though. Throughout the series he's dealt with the various problems that've sprung up, from vampires trying to kill his soulmate to thinking she was dead, it's not really been something that stopped him from being able to act. Bella going, Edward, I think I'm pregnant, and he's suddenly catatonic like a normal 17 year old teenager.
Reading a lot of these posts it seems like a lot of people didn't factor in the time factor either with how everything advanced. Until Edward heard Nessie, she was an it to him. He didn't have any time to get used to the idea that he was going to be a father, that the thing inside wasn't just killing the love of his life. Once he found out that the nudger loved Bella though, and loved him without even knowing him, it caused his outlook on it to change completely. It no longer was the enemy because it loved his Bella, and we've seen he can't really hate anything that loves her, just look at his relationship with Jacob.
The one that really touched me was the memory Nessie shared regarding Edward singing to her while Bella was changing. So he did spend time with her while Bella was undergoing the change(makes it sound like menopause when I say it like that.... ). After Bella was up though, what all we see is Nessie wanting to be with her momma, and that's right before the 3 month jump forward. Edward also shows expressed concern over Nessie's well being because of her advance in age, it was going to affect both he and Bella because they would live forever and it appeared like one of their blessings was going to burn itself out before their eyes.
As a family I also like the idea that the baby doesn't just affect their lives, but also getting to be the most spoiled half vampire in existence, she gets to fill a void for the entire family seems to have had that really never could've been addressed before. Rosalie wasn't the only one that benefited from it, and I like to think Bella knew part of that when she was going through all of it. Esme got herself a granddaughter.. Alice has a baby to shop for... etc... the entire family was taken with her, and we have such a small window to see everything it's hard to wrap your mind around it. I'm sure the three of them did things on their own, but then again, the extended family dynamic of the group dictated a lot of it.
That's probably why Stephenie said that Breaking Dawn would probably need to be two movies if it gets to that point, because there's so much there that we don't get to see. The time frame of it all is rapid but there's a lot that happens that she couldn't describe for us because she was confined to the space of a single novel. I think I'm gonna stop there cause I think I'm rambling now.