im 18 and have been on Birth Control 2 years. i've usually remembered it EVERY day, but for the last couple weeks i;ve been neglecting. My boyfriend and i had sex last monday tuesday and wednesdy. now i have nausea and i've been vomiting for 4 days or so only in the morning. Went to the Hospital because i couldn't get in to see my doctor yesterday, and the pregnancy test came back negative. My last period started 12 days ago... it that too soon to get pregnant? is it possible could i be pregnant? is it too soon to tell? and if not, are there any other illnesses that act like morning sickness?

thank you.