Tested with 25miu hpt, 19 days after sex with first morning urine. result was negative. how accurate is the test? i have irregular periods.

Accurate: The test will usually be positive around 14 days after conception. It's always positive 21 days after conception. Most likely you're not pregnant, but a repeat test 21 days after sex will tell you for sure.

Negative--repeat it: The hpts are quite accurate, but they have their limit--maybe a bit early for the test to pick-up in your case. So, waite 5-7 days and repeat the test. If still negative then, likely it is negative. If positive, congrats and call your doc for care. Good luck.