I agree with Jellybean - don't put of TTC because you never know how long it will take. I was much bigger, quicker second time round cause muscles don't exactly go back to where they once were! in saying that there are so many pretty dresses that are quite flowy so maybe you could suggest one like that? I touwld depend when you go shopping and how far along you were. Your SIL should understand if you are pregnant and if she doesn't then pull out!