Someone Please Reassure Me!

Brittney • Married my husband on August 23 2014! Praying for my rainbow baby.
So my fiancé and I have a wedding planned for April 18th and we've been TTC since march and my heart literally breaks EVERY single time I get a negative. His ex wife got pregnant on b/c with both of his children. We want this SOOO bad and I feel like I'm literally failing as a fiancee. Someone please give me reassurance.