Loaf, if you're still loosing weight I guess the temptation is to hold off until you stop, (huge congratulations on your progress), BUT, I think it's important to buy for the size you are, rather than the size you want to be.
So, given that, what do you want to look like? What's your style? How do you want to look? It's all very well suggesting shops, but they all offer very different things, I have a very pared down look, but others go for more ornamentation or quirk.
Who are you? What's your hair like? What's your lifestyle?
People here are so very helpful, give us more and we can advise better.
I don't think New Look is definitely too young for your age, no shop is, it just depends how you want to look.
(And your budget of course, if you're still losing weight and have a few hundred to spend on yourself then I would go for maybe three of four decent items that will make you feel great rather than spreading it around on loads of cheaper stuff).