Hi,
I understand your anxiety in deciding to become pregnant again after having post-partum psychosis. It is a very difficult decision but I do think that if you are being carefully monitored and treated by a psychiatrist and have a good support plan in place, your chances are as best as possible.
You sound like you have many sources of anxiety - the fertility treatment, worries about post-partum psychosis.... Also, could your anxiety be also due to being off of any medication because of fertility treatment?
The acronym 'N.U.R.S.E' comes to mind as a helpful approach to reducing anxiety (nutrition, understanding, rest, spirituality, exercise) - it was developed as an approach to dealing with women's post-partum mood disorders by Deborah Sichel, a psychiatry prof at Harvard U.
I found it helpful in dealing with having had post-partum psychosis, but I understand that it's helpful in treatment during pregnancy as well.
Have you looked at all your med options to help alleviate your concerns about getting post-partum psychosis again? I know that the chances are there, but for myself and my spouse, we've found it at least alleviating of worry to know that we can prevent post-partum psychosis as best as possible.
I think (anyone do add to this/correct me) that you can take lithium in the last trimester (not before as it is harmful to your baby) to enable a build-up of the lithium in your system. I've talked with my psychiatrist about immediately taking anti-psychotics after birth (I'm not sure though, at this point, if you can take anti-psychotics in conjunction with lithium?).
In any case, I hope that your anxiety lessens. It would be great to hear from anyone that has successfully had a baby after post-partum psychosis. I think that your anxiety (and mine, I know, when I decide to try again for a baby) would lessen if you and us all heard from other women who have successfully avoided post-partum psychosis a second time.
In my case, I only know of my sister, who did have a second child after post-partum psychosis, and is doing great (one child is 6 yrs, the other 3 yrs). Her pregnancy was planned, with her taking lithium immediately after birth. I know she felt quite anxious as well about a recurrence of pp.
Anyways, best wishes - it's such a terrible thing to go through, and I definitely share in how you feel - even though my daughter is now 1 yr. old, the experience of post-partum psychosis is fresh in my mind. It's very scary, but the best we can do is to share our experiences, increase awareness out there of pp, and advocate for continued research into preventing and treating pp.
I just would again really emphasize being monitored by a psychiatrist and having a strong, aggressive plan of treatment right after giving birth. In the meantime, get out and go for a run/walk

, do something relaxing, go to a comedy club....just once you've got a strong support plan and talk with a psychiatrist/counselor about any other ways to alleviate the anxiety, the best you can do is try to allow your body to relax.
Charlotte