I had a neg so I though I wasn't but two weeks later after having constant headaches back pain dizziness sore breast and nausea I had a positive.. so wait a while and test again. I get my test from dollar tree for one dollar a test. They work great.
As I am sure others will tell you, you can have false negatives but no false positives. I was pregnant for 2 weeks and had 11 positive tests, the tests got lighter and lighter which signified a chemical pregnancy. Some women take longer than others to show the increased levels of hcg (the hormone that shows your pregnant in urine and/or blood tests. I tested negative one day and positive the next. Also, if you are stressed out about getting or being pregnant....that could delay your period starting. I would recommend waiting a couple daydvand taking another test. Good luck to you.