not sure how many dpo

mother
on sept 21 i got my peak on the clear blue advance ovulation test .glow says that the 21 was my highest day of 30.00 percent chance i could get pregnant .my other app says when i enter in my ovulation test that the 21 was my ovulation day .here is my problem glow says i'm 1 dpo and my other app says i'm 3 dpo .which do i go by.Its not like i have a high chance i only got to bd on the 18 and the 21 but i still am confused .