Just been doing a bit of statistical work (despite believing that stats don't tell the whole story).
I had a look at 52 pregnancy charts on fertility friend. They were all pregnancies over 42 years of age.
So, here's what I found:
There were 52 charts(that I chose - there were more) of pregnancy from age 42 to 47.
The average time for getting pregnant in this age group was 13.6 months.
Of the total there were 29 charts of 42 year olds.The average for them was 13.7 months.
There were 11 charts for 43 year olds.Their average was 16.7 months.
There were 5 charts for 44 yr olds.Their average was 9.4 months.
There were 5 charts for 45yr olds. Their average was 12.6 months.
1 chart for 46 yr old : 12 months, One for 47yrs old: 17 months.
Of course this is just a small sample so I'm not sure how much we can take from it.
I found it uplifting. To see that many women get pregnant over 40. There were actually 200 charts for over 40, but I only chose a few because there were so many.
An average of almost 14 months isn't too bad. The shortest time in the sample was 2 months, the longest was 80. So it really varies. When in the middle of ttc, 12 months seems such a long time, but if I can have a healthy,full-term baby after 12 months of ttc, then it is worth the wait. 
It may seem there were more successes at the younger end of the scale, but keep in mind it may be because women in the older end are not ttc. Not many women in that age group are still wanting babies, so the stats can be misleading.
I wish FF could tell us how many women are ttc(in our age group) and how many actually get pregnant.