Agreed...definately well cut hair, coloured if you want. Don't drag it all back all the time in a scraped ponytail. Personally, even when mine were tiny, I always wore make up...but that is because I am very pale and feel better with a touch of make up.
I am q slim (no, it's not just luck it's watching portions, what I eat and getting sufficient exercise, be it with a pushchair, in the park , walking dogs, doing housework or doing gym...the lattter I didn't do when they were small as couldn't afford, had no childcare and was too busy!) I agree though, slimness isn't everything...posture and general turn out is (Dawn French always seems to look amazing...but again...good haircut)
Personally I like to be a little in touch with current fashion but that doesn't matter if your clothes are clean, well fitting, not missing buttons etc and you WEAR A GOOD BRA! Don't slob about in old trainers, old jeans, oversized tops...it looks slobby..ok at home but you won't feel pulled together and smart if you are out. I find good boots/shoes make me feel more pulled together.
Finally...confidence in you is everything and can overcome everything...difficult though I know when you feel a frump. Have a look at on line bloggers for fashion..those your age (roughly) and your financial circumstances (though there's always second hand/e bay/make or alter clothes) Shop on line...you can always send it back! Will give you an idea of your style. Everyone I think has times when they feel out of touch and slobby...the trick is to do something about it if it bothers you.
Ok..it wasn't quite finally above...I just wanted to say I'm sure you don't look as bad as you think...because you are making an effort to smarten up. I do think some mums nowadays are over smart though...after all you do still want to be able to run about with your kids and have fun...and you can't do that in some high fashion, dry clean items and smart high heels!