my period is still late

My period is about 25 days late now. I wasn't even feeling horny till about today and went wild. I was thinking about taking a test tomorrow when I get home from school but i wasn't sure. Cause i know that it could also could have been from stress going back to school. Just kinda need advice simce im only 18 and need to know if i need to tell my mom and the baby daddy if im pregnant.