No period

Okay so my diet has been really bad lately so I'm not sure if that's a factor or not? 
I've been really stressed and really tired also. 
Also I haven't used my pill in a while and only started using it again a couple days ago. 
So my last period was really weird and basically I had 2 periods (both a 5-6 days long) within 2-3 weeks. Roughly a month later and I have had my period again yet. My <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">period app</a> is telling me that my period is 5 days late. 
I have had sex with my boyfriend but always use a condom, however I haven't used anything else like the pill. 
But worried. Help?