I am living in Canada. I wear the Hijab. My Question is that since I am living in Canada, I buy my clothes from the stores in Canada. I only buy clothes that do not show the body, like skirts and shirts that do not show or shape the body to wear outside. Is it ok to buy from their clothes or is this considered a following of non-Muslims?

Praise be to Allah, the Lord of the World; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

We highly appreciate this sister's concern to follow Islamic rulings and to adopt the Islamic dress nowadays while most women are not careful about it.
You may wear the dress you are asking about provided the following conditions are met:
a) It should cover the whole body.
b) It should be thick enough, i.e. non-transparent or translucent, so as not to be seen through.
c) It should be loose fitting enough to hide the shape of the body.
d) It should not be a tight contour garment.
e) It should not be similar to the dress of men or non-Muslim or dissolute women.
Know that what is meant by imitation (of non-believers) is to copy some of the things that are peculiar to them.
Allah knows best.