Don't give in to buy more small ones. She can wear what she has and if she wants to wear the small ones she can. If there's only one small one and it's dirty she can decide in the morning what she wants to do about that.
If she's walking around with clothes that don't fit her that's her perogative but you don't have to buy more clothes that look outgrown.
Just make sure to stay detached and nonchalant about it. Do not allow it to become a power struggle.
Hugs, hugs, hugs!
The reason I'm even considering it is because it's not technically outgrown, it still closes and doesn't look TOTALLY ridiculous. Obviously I wouldn't buy that size lechatchila but if the length was still fine I think these would be passable.
It's the overall look of a tad too tight and a tad too short that makes it look not balabatish.
That's why I'm considering this compromise.
And thinking maybe once she gets used to the new length the other ones won't be such an issue anymore