Congratulations on this new journey in your life! I don't know if my experience helps you, but your message touched a special spot in my heart and I thought I'd reach out to you.
I had my transplant 24 years ago and my oldest child just celebrated her 22nd birthday last weekend. My youngest child is 18 years old now. I didn't have lupus at the time (although I am in the process of being diagnosed now!)--so I know that's an added concern and complication for you. However, you also have to understand that in the 1990s, it was still pretty unusual for women with kidney transplants to even try to have a baby--and the worries about risk were very real!
To most of our casual friends and the outside world, I think the whole pregnancy/having a baby thing seemed perfectly normal--especially with the second one when I was in really good physical shape. It was my family and closest friends who had been through all of the close calls, long hospital stays and times where they thought they would lose me that probably had a harder time than anyone else. Once pregnant, my husband and I were so thrilled. Then it was worry. Honestly, all these years later that's what I remember most about being pregnant was feeling worried. There was never enough research to know what effects the meds would have on the baby, I had risk factors for pre-term birth, there were so many unknowns.
But, here's what time and the wisdom of being a mother to these two amazing kids has taught me. It was worth it. Yes, there were risks. And yes, some of those things I feared did come to pass. And one of those kids does have a mild form of autism, which made for a really interesting path in our life--and we'll never know if that had anything to do with my health, meds, pregnancy, pre-term birth...but the reality is that I can't imagine a life without that beautiful girl!
I know that I didn't have as many significant risks to my own health and safety as you may have, but it sounds like you have already made your decision. I wish you all the best in that. Truly, the easiest & longer pregnancy with the easier delivery was the one when I was at an optimum weight, ate well and exercised regularly--not always easy to do!
Now, being a mom---that's a whole other game! One I know you can't wait to enter into! Best of luck!