What Causes Delay In Periods, Sore Breasts And Nausea?

Hi, Im about a week late and I heard you dont produce milk untill a few months into the preg but I have a few ppl telling me otherwise. My breasts are extremely sore and Ive been nauseaous all week and very tired. I cant afford a preg test at the moment and I just want to know is it likely? And is it possible to produce milk that early...or is something wrong with me?