Hi Juliet--I feel your pain.
Just had my 2nd FET fail. We have 3 frosties left, and all have been PGS tested...so we are all a little stunned and confused.
My first FET, I had a septum, so that BFN makes some sense. This last one, my lining only got to 8, which my RE swears was good enough, but obviously something wasn't right. It is true that even under the best of circumstances, sometimes it just doesn't work. If PGS were a guarantee, everyone would do it, right? Unfortunately there are no certainties with IVF, and I have spent the last week absorbing this second failure and feeling very discouraged.
You say you've had two FETs and still have 12 frosites left? I assume no PGS, right? Okay, well I had 12 frosties make it to blast. Only 5 came back normal. That means I could have had up to 7 transfers that were all doomed (if doing SET each time). And I would have felt hopeless--7 failed transfers! I might have given up before finding the healthy embryos. Have you considered PGS on the ones you have left? If that's not an option for you, realize you most likely have some good embryos in there, it just may take longer to find them.
Did your RE have any other thoughts? How is your lining? It's so frustrating when it doesn't work right away, especially when others have success on the first go. You're happy for them, happy to see this can work, but so sad for yourself--totally understandable. But your baby is in there, waiting. I know I've read that sticky thread up there with IVF success stories several times, and there are women in there who had success on their 2nd and 3rd FETs. It happens. Are you putting in one each time or more? I've done SETs and my RE has just about convinced me to try putting in two on the next go. Something to consider.
I think the fact that you have 12 frosties left is fantastic. I always think of the gals who get 1 or 2 embryos total and when their transfers fail, it's back to square one. We are very lucky in that respect.
Hang in there. It's tough but we can do this.