I have very irregular periods. would a pregnancy test 21 days after sex be accurate? i used early response. last period was july 25.

Too soon to test: If you have a positive test at 21 days, it is reliable, but it is really too early to test, as home urine tests are usually reliable at 1 week after missed menses, which are usually 28-30 days for many women. I would recommend testing at 5 weeks or 35 days after onset of last menses. A blood test can be done which is very sensitive and would be reliable 7-12 days after conception.