@Charlie74 and @Green lady, big hugs to you both.
I remember feeling this way before my FET. It was my only frosty and I was scared as all get-out to use it. In the end, fate decided for me - we missed ovulation (my wonky cycle saw me ovulate around CD9, lol) and were forced to put it back a month. Divine intervention maybe, because the lead up the following month was lovely and calm, and sure enough I got my BFP - a brief joy, yes, but a BFP none-the-less. With my most recent cycle in March I only had the one emby and it was transferred in at Day 3. I knew straight away it was a dud, and as soon as it went in thought "Well, nothing for it but to start looking at donor eggs."
Charlie, if you're not feeling it 100%, delay it a month. I think Green lady summed it up beautifully, when it's your last shot you're going to hesitate for fear of failure no matter what month you do it. But I do think you should be feeling prepared and ready before a transfer, so if you need the extra month just take it. At the end of the day a month won't make a scrap of difference anyway. If that precious emby is going to take (and pray God, it will!) it will take just as well a month later