My son's mom showed negative on 3 tests too. But the last test she took she left sitting in the bathroom. About an hour later I went in to pee and there it was. 2 lines. I found out before she did. Try waiting longer for the results, sometimes it takes longer i guess.
And no, if you have a reaction to it, doctors have another shot that will reverse the original shot. Kinda like the "anti-venom", if you will. :p Perfectly safe, just beware the weight gain. :eek: