I'm 5"4' and 130 lbs.  These are definitely small.  I ordered Large because of all the reviews I saw that these run small.  I love the tees, because they're soft and stretchy, but if I hadn't known to size up, any size smaller would've been too binding for me.  If you like your shirts super, super fitted, order your regular size, I guess.  I even ended up ordering these again, but in XL, so that I can have some a little more roomy to sleep in.  I've had two babies, so I like my shirts to be just a tad looser these days.  They did also shrink a little bit.  But they do seem to be good quality, and they're very comfortable, and I love the longer length.