I have to say, changing jobs was the best thing I did.
I suddenly realised, when DD started secondary, that I didn't need to do babies anymore and I wanted my house back. The money was OK for us, but only because DH subsidised it really, with his wages. There came a point when enough was enough. I know your DD is coming up to secondary age Katy, do you think its time for a change?
Work is great. (food shopping is suffering a bit, but hey!) I get up and go out, lookiing posh, with high heels on and I feel important again. I know cming is ridiculously important, but its a different kind of important. I do miss the little ones, but its always a case of 'the grass is greener'.
The major difference is financial though. I get paid the same every month, without fail, without asking or chasing and no worries if I'm off sick.
I bet this isn't very helpful at all, but its food for thought.