I developed severe OHSS during my fresh IVF, so didn't get to experience a fresh transfer. My eggs were very poor quality, leaving me with only 3 embryo's out of 25 eggs. They were below the standard freezing quality but after much persuasion, we had them frozen on day 3. There were two 4 cells and one 8 cell, all of which were very fragmented. We were warned throughout treatment not to get our hopes up as the most likely won't even survive the thaw, let alone create healthy children, but we stayed strong and positive.
Naturally we were all nervous come thaw day but our little fighters amazed everyone as all three survived. One of the 4 cells lost a cell but the other two remained in tact, so we had a 4 cell and an 8 cell transferred. Again, came the speech - just because they survived the thaw, doesn't mean they will implant.
11 days after my 3 day transfer (3 days being from the fresh cycle, they were thawed in the morning and transferred the same afternoon) I started cramping and bleeding heavily. I thought AF had turned up but had to test to 'complete' the treatment cycle. We were both stunned when the test was a very strong positive! As were the clinic!
We had our 7 week scan booked in for three weeks later, but the night before, I again started to bleed heavily. We thought that we were loosing our little fighters. We were shocked once more at the scan when the lady said 'there's your baby!' We were even more shocked when she went on 'and there's it's little buddy!' We had to go in two weeks later to check them as vanishing twin can be pretty common, especially with bleeding. They were both there at 9 weeks
Throughout my pregnancy, I had bleeding spurts and then my waters broke at 29 weeks. Following a weeks bed rest in hospital, our gorgeous son and daughter were born at 30 weeks. As they were tiny, they had a 6 week stay in SCBU, but they will be 3 years old next month and you would never know (or appreciate) the journey that they have already had.
So, in short, if you have embryo's put back, there is always a chance of them implanting, even if the odds are against them. Likewise, even if they are perfect, textbook embryo's they may not implant at all. I always say you have a 50/50 chance regardless, either it will work or it won't.
Good luck with your FET!!