Can doctors clinic urine test be wrong

I have never been late on my periods for past 20 years . We have been planning for our second kid for past 3 years . This month i am currently 4 days late as of today .. I went for a general appt to the clinic and the doctors assistant took a urine sample since i was late and it was negative .. I have got severe back pain and lower abdomen pain and cramps past 1 weeks but no signs of AF.. should i retest after few days or the doctors clinic urine test is accurate ☹️☹️