i woke up and threw up the food from last night...

ok im 14 , and i just posted a picture on facebook of me and my boyfriend kissing and my sister yelled at me i feel really feel stressed out from it. the next morning i woke up and threw up the food from last night and stayed home and didn't go to school. i feel tired more and had one dizzy spell getting up from school to after i took my shower. i don't know if im really stressed out or am i just pregnant . ( i had my period 2 weeks ago and i haven't had sex after it .