How late can your period be before a pregnancy test actually reads positive?

Kayla • Hello my name is Kayla and my husbands name is Michael we have been TTC for almost a year with no luck.
The reason why I ask is because I missed my period this month my hormones are crazier the period hormones (I freaked out on my boss and almost throat punched him then cried about it )  my boobs are sore   I have really heavy thick (creamy) CM. I had this consistency threw out missing my period tested several times with one extremely faint positive and a ton of negitives  could you ladies give me some advice on what to do ??