What I have learned, being an unusually sized woman, is that it is NOTHING to do with you.
Clothes merchants are businesses, businesses are out to make money, therefore the cater to a certain range of styles, sizes, and prices. It has NOTHING to do with you as a person... it just has to do with the percentage of people who have bodies that are identical to you.
I'm 6'1. I need an extra 4-6 inches of length on shirts than most people (maternity shirts are AWESOME... the ones that just add length). I have a 37" inseam. People look at me and say they "Wish blah blah blah". Really? Try on a dress. Is the bulgy area for the boobs over your sternum with your breasts skooshed into the area meant for the ribcage? The wide area for the hips over your waist making you look pregnant? The narrow area for the legs over your hips? ((I call 'off the rack dress shopping' the "lasagna noodle effect... curves are in all the wrong places)). EVER see a pair of pants in the women's department with a 36 or 38 inch inseam? My best friend is FIVE two. She has the opposite problem in things being sized for "the majority". If she shops outside of the petit department she gets the lasagna noodle effect as well!!
I can shop maternity and I can shop in the boy's department in the US... otherwise ALL my clothes come from the EU (mostly the UK and Italy). Purely because those are the only places that I can buy clothes sized for 6 foot tall (Scandinavia, yay) women. If I was "shrunk" down to 5'1 instead of 6'1 my proportions when I was thin would have had me at a 0. Instead I was a 9/10. At my middling weight I'd be 6/8 but instead I'm a 16/18.
There are SOME stores here in the US that have tall sizes... but they come out looking "weird" on me (SOOOOOOO weird). So I shop at stores that have clothes that look good on me. It has nothing to do with ME... it has to do with their stock.
If you have half a dozen options aside from Target, shop there :)