Missed period of 5 days

So my cycle is typically 25 days with 5 day periods. My period was supposed to end yesterday. Meaning I missed my period completely. I know people can have their periods pushed back for many reasons but my period is always always on time. So I have tested the day of my missed period, 12th of may, and today, which is supposed to be my missed period completely , and all have came out negative. I had sex on the day where I had a 27% chance of being pregnant, which was cycle day 10, it is now cycle day 31. Meaning I would be 3 weeks past conception.  I am not trying to conceive but this is just weird to me because my periods always regular. What do you think is going on? Do you think it's two early for the test? I used first response. When would you recommend to test again?? Thank you!!