Sounds like you're making the right steps!
Do you do any exercise? It's always hard to fit around young children, but if a DVD at home is all you can manage, then that's better than nothing, isn't it? I used to use Davina when my eldest was a baby and I couldn't get out, and have also used the 30 day shred when stuck inside, and both have been really effective (and the 30 day shred is only 20 mins, but you are supposed to do it every day).
Anyway, I find doing more exercise makes my skin better, and I feel better about myself, so it's a double whammy. Then you start seeing effects on the outside of your body, and it's a triple whammy.
Good underwear that fits is always a Good Thing, and in terms of clothes shopping I do tend to buy more expensive stuff, but then I end up buying fewer clothes, as the ones I do buy last better and hold their shape and colour on washing (I try to buy natural materials as much as possible, which seems to be getting harder on the High St with way too much polyester). My one caveat is Primark £2 vests - I bought about 5 one year and they're still going strong 3 years later worn constantly. In fact I'm only thinking of replacing them now, they've been fab (no such luck with any other Primark clothing though).
Getting a hair cut and colour (even if colouring yourself) always makes me feel fresher, and bunging on some make-up can help (although I go through waves of this - I tend to wear no make-up in the summer when I'm tanned). 1 small step at a time...