My last period 09/03/15-09/08/15. my bf and i had sex 14 days out of sep. bbt today is 99.1. preg tests r neg. could i be preg? periods r irregular

Yes!: Yes, you could be pregnant. UPT have a known false negative rate. The rates increase the sooner you do the test. If your menses are irregular, you need to discuss your desire for pregnancy with your doctor. There are medicines available to help increase your chances of pregnancy. If you do not desire pregnancy, you must start contraception immediately.