Testing pregnancy too early

Hi everyone! This is my first post ever! 😊 my husband and I have been trying to conceive for about 6 months now... we’re trying not to stress about it and just have fun! - I had an x-Ray appointment and was required to take a pregnancy test before I could proceed- i took a first response test and it said negative - however, my period is not due for 8 days! how likely is that test to be completely inaccurate? Or has anyone experienced a complete negative test only to find out they were pregnant after testing days later??