Stressing out possible pregnancy

Im 18 and around a week late for my period. Im afraid I am pregnant. Mostly for the fact that my mother had me at 19 and I told her I would never be like that. My whole family says I need to wait to have children until im financially stable. Im afraid of being a disappointment and them not accepting it. I never planned on getting pregnant but I knew the chance when my boyfriend and I have sex. Im not sure if I am or im very stressed. Please help me with advice!