Pregnancy

So I am 17 almost 18 years old and I think I may be pregnant. My ex fiancé broke up with me a little over a month ago and I had my period last month but it didn't come this month and I have gained some weight which is unusual for me because I am only 4"10 and weight 90 pounds but as of yesterday I weight 102 and I haven't broke 100 pounds in 4 years! I took a pregnancy test 2 weeks ago and it was negative but that was before my missed period! I'm terrified to take another test and if I am pregnant I don't know how my ex will react, does anyone have advice for me and what I should do?