Three pregnancy test, possibly vapor lines??

I have taken numerous pregnancy test the past few days. All of them looked negative at first, but after the ten minute mark, every single one of them popped up with a thin blue line. Is it possible that every single test could be vapor lines? I don't want to get excited just yet. I guess I would just like other opinions, before rushing to call my doctor. Glow says af shouldn't be here until the 15th, but all except last month, I've been fairly on time with it coming between the 5-7 of each month (last month I was late definitely due to stress).​​​