I got pregnant right before 42d birthday with my 5th IVF cycle. I was going through fertility treatments with a lot of obstacles: I was down to one ovary after surgery to remove a tumor, I had undergone six months of chemotherapy at 39, etc. Two RE's told me to give up and I was ready to, but my husband said no, we'll try one more time. I had a healthy, beautiful DS at 42. Fast forward to March of this year (three years later), I found myself unexpectedly pregnant naturally at 45! I just turned 46 last week and my due date is in November--everything has gone great so far. I thought our first child was a miracle, but this is truly our miracle baby. I am almost hesitant to share this story as I think it is likely an aberration, but it is possible even in difficult circumstances.
I hope you have similar success--it is very difficult to know when to give up on IVF.