I'm 21 years old, and have been on birth control since I was 16. I got off about 4 months ago and my boyfriend and I have been trying to conceive. I was supposed to start Oct 22, but still no period. I just feel different. Occasional nausea, mild cramps, and leukorrhea. I have taken 4 pregnancy tests in the last week and they are all negative. I have also been sneezing constantly. Could I be pregnant?