Weak positive.. Whats the possible reason??

Hello everyone!! I got my PT done on January 22 but the line was very  faint so I figured thats it's probably because i tested early as it was only 5 days that i missed my period. So, I tested again at home on January 29, still the line was not too dark. Took a lab test and they said it's a WEAK +ve. I am really confused?? Whats the possible reason?? Help!!!