this is quite tricky. i mentioned earlier that you should wear baggy clothes, but i think i need to be more spesific.
how you dress is very important. you dont want it to look like you are getting deadly thin. people might get suspisious.
try layering it up! wear tank tops under tee's, or two long sleeved shirts. also try wearing a sweatshirt--BUT this should not be a loose sweat shirt! if its a big, loose sweatshirt it will make you look even skinnier! with pants, really your legs look the same in anything, but try to avoid wearing boots/shoes that are 'puffy'. like furry ones or ones with indian tassles, these will draw attention to your skinny legs.
you might be woundering why i want you to look fatter than you really are, isnt the point of pro ana to look and feel skinnyer? yes of course! BUT you cant really BE pro ana if your parents send you a recovery center, or watch you eat because your so thin! if you are over weight, then lose weight first, and ONCE you hit the under weight line, THEN you start dressing fat, because it will make you look like you are a normal healthy wieght! if you are allready normal/under weight, you should start dressoing fat NOW. next time you go shopping pick up some thick fabric blouses, or some (my favorite choice) V-necks that need a tank top underneth.
good luck! ~E