Am i pregnant????? missed period, vomiting, emotional?

im 19 and my period is a week late exactly so far. im normally right on time unless im stressed when im stressed i have been a few days late up to 3 or 4 but never this late. i am a bit stressed with exams and school. i have always used condoms with my boyfriend. today i went to a resterant with him and his mom that we go to every week. i was eating ice cream that ive had before i only ate 3 small bites and pushed it away saying its making me feel sick. i normally love that ice cream. anyhow i went to the bathroom sat on the floor for 10 mins during that time i was having hot flashes his mom came in asking if i was ok i said i wasnt feeling well and we left i ended up throwing up out side the resterant it was snowing like crazy and i was wearing a tank top (i took off my t shirt, hoodie, and jacket i was too hot) i was sweating in the snow in a tank top and when throwing up i started crying idk why i felt better after....and i noticed all week ive been crying randomly for no reason my boyfriend said something and i started crying this week, i saw narnia down under and cried!!!!!! it wasnt that sad!!! anyhow i felt alot better after being sick and im not likey the same foods stuff i love im not interested in anymore and im very emotional. i havent had any other signs thats it so far....when should i take a test? and is that a strong factor of being pregnant? his mom asked me today if i was pregnant because ive been so emotional lately.