annaleigh, as Smittie suggests, you have to get the smallest sizes EARLY in the season because they sell out the fastest.
There are plenty of 0's, 00's, XS and XXS's available online (if you shop early!). And you can shop fits that are narrower than others.
Jeans are not hard to find in size 23 to 25 online.
Retailers with narrower fits:
- Karen Millen
- Zara (although sizing is VERY inconsistent)
- Scotch & Soda
- Boden (sometimes!)
- Theory
- TopShop
- Levi's
- Most designer pieces and premium denim labels
- Simone Perele has smaller band and cup sizes than most. Pricier though.
As someone who is slight and regular height, I also need a small size and a narrow fit. At 5ft 6, petite clothing is desperately too short for me. I do a lot more altering than I used to on pants and jeans to create a perfect fit these days because size specifications are wider than they used to be. A US0 today was the same size as a US4 twenty years ago.