late but no positive test

Kara
So my cycles have been basically 26 or 27 days for the last 5 months and I'm on day 29 and still no period. 
Wednesday, the day I was supposed to start, I had awful cramps like I thought I was gonna start and still nothing. 
Took a test today, thought I maybe saw a faint test line but I think I'm just seeing things because I'm never this late. 
Any advice?