I think it's great that you care enough about her to question the right path to take. That shows that you have a wealth of empathy, and I admire that.
Her doctor does sound off the wall. A women going through infertility treatment is often advised to got to a few different doctors (RE's--reproductive endocrinologists) to get second and third opinions. No doubt she does have endo--but there are doctors who's practice is built around getting women with endo pregnant and sustaining those pregnancies.
Maybe you could look some info up online for her and show her it. Since she has been pregnant before that is a good sign, but we all know that is only a peice of the puzzle. Does she have a good grasp of human biology and what is happening to her body? There are lots of books out their written for the lay person--there is probably one called "getting pregnant with endometriosis" that she could read to see what her options are.
It does sound like she is in Lala land about buying the baby stuff now. I think she is just terribly excited about it and does not want to face the other negatives that are going on so she is pouring her energy into this. There is not much you can do for her except be a friend to her--and catch her if she falls and does not get pregnant. This may be one life lesson that you cannot teach her--she just has to live it and feel the pain. Because if she does not get pregnant she will be feeling pain no matter if she is buying baby things or not--that part is actually irrelevant.
Sometimes posting at Mothering I feel like a total oddball because of my infertility past. Talking about "being worried I am pregnant" is just so NOT a part of my reality and frankly never was. I also know that without the fertility meds that I took I would not be a mother to Matthew and Samantha--and many people here have such disgust and distrust (mixed with a boatload of misinformation) about fertility meds and what they do. Because of this I often post on a parenting board made up of women who have been through infertility treatments and are now parents--they know the "lingo" of infertility as do I. There is a whole other world out there filled with phrases like "IUI, Gonal-f, IVF, ZIFT, GIFT, Clomid...." that even the most science disabled person can learn about if they are forced to by life circumstance.
You might want to point her to that board--there is an endo board there with tons of women sharing info on what they are doing to get pregnant and the obsticles they are facing. Many go to certain doctors known for removing endo (through supressive drugs and surgery) and then use fertility meds to get pregnant quickly before the endo grows back--and are very successful with these techniques. Here is the board:www.fertilethoughts.com
Here is a thread from that board about "endo success stories"http://220.127.116.11/forums/showthread....threadid=60649