I'm a bit confused, can you confirm
when was your last normal period, how long did it last?
when did you have unprotected intercourse?
when did you use the pregnancy test
If the period is normal and you had intercourse only 5 days before period then risk of pregnancy is slim, but not zero
If you had intercourse during the days 10 to 16 after your last period then this is high risk of pregnancy.
Having intercourse on 6th May, with next period not due to 25th means that this was about 4 or 5 days before your most fertile time so again risk of pregnancy is low but not zero.
You would have to wait to test until at least 25th May and it is still possible to get false negatives for at least 7 days after this.
If the pregnancy test is negative on 25th then we cannot be sure but if you have a normal heavy period lasting 4-6 days then I would say that pregnancy was very unlikely.
If the bleeding was very light or did not last long, then I would suggest redoing the pregnant test 5-7 days after that.
Its at least two weeks, and often longer so we usually say the first day of the missed period as a starting point.
Can I just check, do you still use birth control pills?
Yes, if you only missed one pill and it was not the first tablet of the month then it is highly unlikely that you are pregnant, so a normal bleed and a negative test will be reassuring in that regard.
We can't guarantee accuracy of pregnancy tests within the first couple of weeks but when you are on birth control then you should not ovulate and your periods are withdrawal bleeds rather than menstrual cycle due to lack of pregnancy.
If you only missed one pill, then you are at very small risk of pregnancy so try not to worry and do the pregnancy test just for reassurance.
We normally say that if you take the pill for 7 days then you are protected. Although you have may have missed two tablets, they were separated by 7 days so the chance of pregnancy is really not that high.
Try not to worry for the next week, ask your doctor to run a blood test on 25th May if you want an accurate test and do not want to wait to repeat a pregnancy test.
Repeat a pregnancy test 4-7 days after the first. If your period comes in the 25th or 26th then it does not matter when you take the test because you are highly unlikely to be pregnant, but you could wait till 28th then test at that point.
If you have a normal or heavy period on 25th then this means the lining is shed and the chance of pregnancy is very very low.