Pregnancy symptoms

Appetite has decreased I’m always nauseated have thrown up after eating a couple days! My period is usually around the 4 I got it on August 31 stayed for about 2-3 days it was very light! Could I be pregnant? I’m very nauseated all the time?!!! And have sore breast! And have major backache! My cousin messaged me and said I might be pregnant ! Can babies sense if I’m pregnant?