Faint line advice

Sandals

This morning I took a pregnancy test - one of the HCG test strips. There was a faint line on the test. Enough where anyone would see it, but not confirmed dark enough. Maybe an Evap line? I don’t know. My period was supposed to come on the 13th. I bought a dollar store test today and took it about an hour ago and there was no line. I’m so anxious to know, but idk. How often do false positives happen?

Update: tested this morning and no line. At least 4 days late with my period giving an extra few days as sometimes I don’t get it exactly on the day. Idk if that is a definitive no or if I just need to wait a few more days. I did use a dollar tree test, but they have always worked for me, so it might mean not this month. :(