Help !!!!

So I’m scared I might be pregnant ok. I’m 16 and my car isn’t working and I live 30miles out of town. My period 5 days late and it never is . My doctor told me I have impetigo and I need to take the medicine for it. I read that pregnant woman shouldn’t take it . My step mom been bugging me to take it. I was going to take it right when I started my period. And I was going to start birth control this month so now I feel fucked. What do I do???? I can’t tell my parents I think cuz if I’m not then I get chewed out both ways