Missed period

How long after your missed period did y’all take a pregnancy test and it came up positive? I’m two days late and the test is negative. But i feel nauseous and fatigued. I had some light cramping this last week but no bleeding. I’ve four kids and can’t remember how long after a missed period i got a positive pregnancy test. My test are always faint. I’m worried if I’m not pregnant than there might be other issues.