Is Feeling Sick Then Not Sick Sign Of Pregnancy ?

I Am 18 Years Old And Im Not Sure If Im Pregnancy Or Not . I Would Feel Sick One Minute And Then The Next Not Sick Then It Turns In Burps Then Hiccups , Also Im Losing Weight Without Trying And My Appetite Of Eating Has Decrease A Lot , Im Barley Hungry I Have To Force Myself To Eat Dinner . So If Any One Can Give Me A Little Advice And Tell Me If This Is Normal Or Not That Would Help So Much !