embryo grade success . calling out embryo experts !!! help!!!

Sheets • Ttc #1 3 years of marriage . Getting desperate ! But keeping the faith
Anyone had success with grade 6BC embryo ?? This was my first FET on Wednesday . This was a grade 5AB before thaw and I'm so mad at my RE for putting it in when he knew it had downgraded  when I had 3 other frozen ones 😰