I just really need advice

So ladies I am about 8 days late for my period. I took a test one day late, 5 days late and then today..... All negative. My periods are never late. I'm not really having serious symptoms. Just a little tender in my breasts, not much of an appetite, a little headache and also feel light headed. I just want to know if anyone has experienced this and just missed a month of their periods or is it that I am pregnant but it's too early for pt to detect. I just need help. My appointment with the doc is Friday for a blood test if no period shows but I just really would like some advice from you lovely ladies! Thank you in advance!