If you wear lolita everyday it's called being a lifestyle lolita. (kinda, a lifestyle lolita wears lolita clothes everyday but also listens to lolita music, eats lolita things, has a lolita room, ect.) You can be lolita if you only have a couple outfits. and don't worry about being a cosplay lolita, there is no such thing. I wouldn't say that you should identify yourself as lolita when your not wearing lolita because that can really make other lolitas mad. This site lists all the ways that you can avoid being a "cosplay lolita"
http://www.lolitafashion.org/cosplay_lolita.phpFor all beginner lolita I can not stress this enough, NEVER say lolita is a costume. It is a style and to say it's a costume is to say we dress like this for attention, and this is not the case. This also might help you find cheaper lolita outfits.
http://www.lolitafashion.org/budget_lolita.php