What is going on?

let me start of by saying hello ladies i am new here and i am 20 years old been married for two years and I'm ttc janurary 18 2017 I had a miscarriage due to i had placenta previa and had a car accident soni lost my baby boy at 15 weeks pregnant, now after wards i got the nexplanon put in and then i got it removed on Dec 26 2017 because by husband and I agreed ttc now on Feb 7 2018 I got my first period it ended on the 13 or 14 around there then i ovulated the 16 to 22 and we had intercourse now it's March 10 and i am 4 days late but got a negative on a pregnancy test which was first response six days sooner one but i have all these symptoms nausea, constipation, moody emotional and just sick to my stomach. What is going on?