Help.

The last time I had my period was valentines day. I was supposed to get my period 13 days ago as it says so on this app. My periods are also irregular sometimes. Me and my boyfriend didn't use protection but he did not ejaculate in me. This app also said I have a 7 percent chance of being pregnant. I'm getting really worried..

UPDATE:

Alrighty, I took a test today and it was negative thank god. But I am now 20 days late on my period. This has happened to me a couple times now where my periods are drastically irregular so I will be going to be checked by a doctor and find out what's wrong.