Negative...then positive...??

Okay mammas I am very new to all this trying to get pregnant stuff. My husband and I have only been trying for three months. It is so hard to not take every little thing as a pregnancy sign and get hopes up.

But I'm suppose to start my period this week, really any day, and so far haven't (but not necessarily late). So I took a pregnancy test and it was negative, but me and my crazy self checked it again a few hours later and there was a faint line, making it a +. Could that mean anything or is it just because it's expired and random things happen to it?