BFN what do I do??

So, I have day two, missed period and my partner and I were definitely active during my fertility window and ovulation, however i took a test this morning and it said Not Pregnant. I am sad because my partner and I were so excited to have a child together. I feel that i got my hopes up... how do you deal with a Not Pregnant result when you’ve been actively trying?? What tips/advise do you have?!