Thanks everyone for your responses. There are some really good points there...

We have the house and car already. We bought our house and car based on the plan to have three so we're covered. It has only been recently that I have been doubting my ability to properly parent three kids... given that I seem to be a lot snappier and grumpier with the two that I already have!

Could also be coinciding with my return to work...

DG... I can't imagine what you are going through right now. We are all here for you...

The first part of your post resonated with me... when DS was born I felt straight away that I'd be doing that again. And yep we went and bought the bigger house... and we've waited longer than when we conceived DS... but my body's not ready anyway right now so we didn't exactly have a choice.

Mrs NB - a few people have said that, that 2 to 3 was easier than 1 to 2. I'm hoping that DS and DD will play together nicely when the new baby comes along.

Did I just say "when"? I meant "if"...