Stress sometimes delays periods, and you are not regular anyway. But how often do you have unprotected sex? Did you have it during your fertile days?
Periods were 29th, and now 10th - did that suddenly happen, or was it gradual over time? If you have a 28-day cycle, then in 9 months the 29th could become 10th:
- 29-Jan 26-Feb 26-Mar 23-Apr 21-May 18-Jun 16-Jul 13-Aug 10-Se
However anytime you have sex there is a chance of pregnancy, and so if you are still having unprotected sex you could still get pregnant. The test will only show up after implantation, so if ovulation were significantly delayed, you could still get pregnant.
I hope this helps as a start.