Does Having Unprotected Sex While Having Irregular Periods Cause Pregnancy?

Hey, I was just wondering . I have irregular periods and have been trying to track it with help from a phone app called my calendar that has been rather close by 1 or 2 days. my menstrual cycle is on average 55 days . Although me and my partner are not trying to convince we have been having unprotected sex for around the last 5 months with so far no pregnancies. I was just wondering my period has not yet came this month and was due the start of . I ve had psm like symptoms some more server then the usual. What my chances of being pregnant are and how concerned about this I should be ? I m 25 years old.