I am having a lot of pregnancy symptoms on and off and my period is over three weeks late and no sign of it and im getting a negative result?

Trust the test : A pregnancy test can detect a bhcg of about 20. Your bhcg roughly doubles every 48 hours. Let's say the first day you took it you were barely pregnant with a level of 19. 48 hours later your bhcg would be 38 which is way above the level for a urine pregnancy test to detect it. Home tests work really well and can be trusted. Repeat and if negative then you are not pregnant.