I was wondering when a Toronto thread would pop up, thanks! I'm technically in the 905, but these tips still help =).
If you're purchasing from Pacific Mall or similar Asian boutiques, be really wary of the quality... I purchased a pair of black skinny pants a couple weeks ago, and the waistband has started to disconnect from the pant, and the back pocket is coming off... This is after 3 washes.
Salespeople also tend to be extremely pushy. Some shoes in sz 4 are available, but it's pretty rare.
It should be noted that there's a Holt Renfrew outlet in Vaughan Mills - It's in the suburbs and in the 905 area, but the mall is pretty great for shopping overall - They also have a Browns/B2 outlet, Gap outlet, Le Chateau, Laura (Petites) and a Banana Republic outlet (No specified Petite section). I saw Manolo Blahniks for sale at the HR outlet in a size 4.5 last weekend.
Speaking of Banana Republic, I have seen a small number of petite items in store - But these are mixed in with the regular merchandise, so they can be very difficult to find.
Other stores that carry size XXS (besides the upcoming JACOB collection) include Le Chateau, and of course, Aritzia.
There's a good sized Le Chateau outlet at Woodside Square in Scarborough, located on McCowan, just north of Finch. While it is an outlet, there is a wide variety of sizes available for sale, so it's not too difficult to find XS or even XXS in a style you like. I've found, however, that the armholes run really big, even in XXS, but this is a great place for dresses. I've found that Le Chateau shoes tend to run a little small.
JACOB - There is an outlet in the 905 area at Highway 7 between Warden and Woodbine (First Markham Place), but if you were planning on making a trip, I'd advise against it - Small sizes are rare there =(
The discount store Winners has a Petite department, with petite clothing from a variety of brands if you like the hunt. I'd think the similarly-styled Designer Depot would as well, though I don't know for sure. Vaughan Mills has both of these stores.
The Little Bra Company - According to the TLBC site, the following stores in Toronto carry their products:
1. Melmira Bra & Swim Boutique
3319 Yonge Street
Toronto ON M4N2L9
2. Secrets From Your Sister
560 Bloor St. W
Toronto, ON M5S 1X8
3. Secrets From Your Sister
2501 Yonge St.
I recall from the AN blog that a commenter said one of the Secrets From Your Sister locations was no longer carrying TLBC, so I'd call ahead before making a visit.
There's also a store named Mateo in Markville Mall (905 area - McCowan and Highway 7) which sells shoes down to a size 2.5, mostly Italian brands.