Could i be

So my last period was August 20th and for about 2 weeks now i have been having nausea and vomiting every morning and then it goes away, went to the dr and neg pregnancy test and my fiance and been getting sick for about a week now and he said he hasn't felt like this since his ex wife was pregnant and that was 14 yrs ago and it takes a little while to show up on pregnancy test with me. Next period on sunday the 20th. Please help.