According to the US clothing industry, size 14 starts plus size. Target does not have much plus size stuff, since they are rather snobby, WalMart is good for casual stuff. Torrid is good for trendy clothes in plus sizes.
In terms of chains of plus size stores, obviously Lane Bryant is the biggest in the US. Your profile says you are in Buffalo, if that is right you could also cross to Canada to take advantage of the exchange rate. Biggest plus size chains here are Addition-Elle and Penningtons. Reitmans carries plus sizes in some stores,and as in the US many pieces in 'normal' stores should still work for you
My gf just picked up some camis from Torrid for the spring and summer and loves them. They seem to have more deals for her than LB, at least recently anyway.