Help? Getting concerned

<a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">Eve</a> says my period is 17 days late. I'm 16 almost 17. I've always had safe sex. can I still miss a period at my age? or should I take a test? my friends say it's stress and I think it is cos school has been hell and home life is just as bad. and don't even let me start on my love life. I'm thinking it'll come soon cos my nipples are very sensitive at the moment so maybe?