Talk to Gynecologist on Gynaecologist

Married 26 years old. No medical history. I have irregular cycle, but periods always remain for 7 days.

Problem: I have tested for pregnancy on 24 sep, which was 30th day of my menstrual cycle and it came out as positive with a faint line on 2 strips of same company. Previously i also did my test from same strips and they were negative all the three times. So I believed that its an accurate strip with true positive. But then at the same time after about half an hour or 1 hour I bought other strips to cross check but it was negative.. I thought that this strip is not that much sensitive to early detection. Then after two days its again negative on 3rd company strips.. Today I started my periods on 35th day of menstrual cycle with proper bleeding.. Now my question is that why it came positive on two strips as false positive is so rare and if the strips were not good then why those same strips gave negative 3 times previously when it was actually negative. Should I go for some