help!

Heather
I've had brown stuff since last week and I thought my period would have started by now, but it hasn't! I usually have brown stuff for a few days before period, but I feel like not for this long! Glow says I'm supposed to start on the 15th, but I don't even have cramps or anything this week! I'm all worried that something is wrong!!  Can anyone give me their opinion? I want kids so bad!!