I think I posted this somewhere else one time, and I read it in "Up the Duff", she writes about all those comments (and any with regards to breastfeeding or not, or co-sleeping or not, you get the idea):

It's about them, not about you.

People can judge you and say it won't be easy having two so close - when is having a newborn when you already have another child/ren easy? That's not the point, really, is it? I agree with the other ladies here, it will be great to have such close siblings. You and your DH are happy and Chelsea will be too! Hope you can manage to ignore them.