The only place I found in-person were thrift shops. They don't all have dressing rooms but I just wore a dress and tried pants on that way.
There is the Maternity Warehouse near Yorkdale. It’s a bit hard to find, and looks like a creepy warehouse lol but the sales person, Ran, was super sweet and helpful. The quality of the clothes are pretty good and there is a wide selection (jeans, tights, dresses, tops, nursing bras etc.). The prices of the clothes I bought ranged from $30-$60. To be honest though, Amazon has been good for me too, even though I didn’t get to see them in person
I found nice maternity clothes at H&M in Eaton Center. Otherwise if you are ready to spend some money on mat clothes then you can go to Carry Maternity in Yorkville.
Carry has some really nice stuff, but not cheap. H&m has a small maternity section, I love the maternity tees!
H&M has a fabulous selection but mostly online. My advice for pants is skip the maternity pants, my fav right now is Lululemon Align, Aritizia Butter Leggings and Champion Brand Yoga Fit Curvy Pants. They are all so comfy and stretch like no maternity pants have been able to.
Oh and Walmart has the Bravado maternity bras that are really comfy.
Also I just got the maternity leggings from knix, they are possibly the most comfortable pants I have ever owned
There is a big section of maternity clothes at the Walmart in Etobicoke beside Sherway Gardens
The only place I've been able to find a few things in person is old navy. But only in the clearance section as they don't typically sell maternity instore it's usually online only. And some walmarts have a few items in store as well.