Good work coffee mug. Despite the lack of help from anyone, I'd say you pretty well hit the nail on the head.
There are more hidden expenses than you think. Just having 2 mobile phones in the family can really add up. Plus cable TV equivalent. Plus public transport. Plus a house of any decent standing is more like 40k per month. The list goes on!
One might say that your figures were quite conservative, and it would actually be worse off than your predictions!!