I NEED ANSWERS plz

Have you ever been late on your period and still got a negative preg test?

Me and my husband have been trying for our 4th baby. I’m currently now 3 days late and still negative but I swear I see a faint line one on of my test but idk if im going crazy. Question is

If this has happened to you and you were really pregnant how long did it take for your test to come back positive.