Very cute! For a first fic, this is rather good! :)
My one quibble would be the switches between first person and third person, but it wasn't that hard to follow. It just it makes it easier for the reader if you keep it consistent the whole way through, or very clearly put in a break to show you meant to do a switch in narration.
That aside, this was really enjoyable, the kind of warm fuzzy story I was in the mood for!
Keep up the good writing! :)

I knew it! I knew she was pregnant!

There are a lot of spelling and punctuation errors in this. You might want to consider finding a beta.

I like that Zuko wanted to keep the baby. :)

Overall, this is a good story.
Waterbender

This was really cute! I hope you make a multichaptered fic soon :)