You could absolutely be pregnant if your test came back negative. With my 2nd pregnancy, I was getting negative results from the at home tests, but I called my doctor anyway because of other issues I was having. I mentioned that I thought I might be pregnant because my cycle was all goofed up, and when they did the test, it came back negative as well. They sent me to get a blood test done, just to be sure, and it came back that I was pregnant! You just never know! I'd say that if you don't have a cycle by the 25th, call your OB doctor and let them know what is going on. There may be something else happening but it is better to be safe than sorry. :o) Good luck!