Scared

So I'm 20 years old and me and my fiancé have been having unprotected sex for over three years now. I miscarried two years ago because of stress. My period was due July 27th but never came. Three days later I spotted and the second day I think there was blood but the next day there was nothing. I'm now two weeks and one day late. I took pregnancy test on July 26th and I took one August 5th but they both came out negative. Could I be pregnant or is something else wrong? Like I have all the symptoms of pregnancy and my sister even thinks I  cause she's pregnant too. Can someone help me please!!!!!😥