Clear blue digital neg ... But got faint line

Elizma • Having our rainbow baby girl end of January!! God is soo good
Im 18 days late my boobies hurt and having some cramps light ones and heart burn .... I took 4 clear blue digital but all neg ... I had a normal test just the usual nothing digital about it got a faint line like verry light ( took test at night ... First didn't see the line and later took it out again after some time and there were a fiant line now im confused??