FET failure after trying for second child

Hi all, let me know if this isn't the right place to post this question. I just found out my first transfer (frozen, euploid) after having my 14-month-old son failed. We used the same protocol that was successful not only for him, but the transfer before that (which ended in a MC). I'm trying not to spiral too much, but now I'm freaked out that this protocol we thought worked well for me just won't work anymore for future transfers. Has anyone been in this position? Would my pregnancy have somehow changed the protocol that would work best for me?