Hi Livvi,
I have had a bilateral mastectomy and always thought I would get nipples. Trouble is, I decided that I wasn't too unhappy with the way they looked, and also thought I wouldn't want to risk possibly ruining very good implant reconstructions. What I have done though, is to buy some fake nipple tattoos, and they are really good. They come from the UK, in the mail and don't cost much. The site is Tattooforaweek.com and if you look up Areola nipple tattoos it will show you 2 pages of very realistic different coloured tattoos. I intially bought a selection of what was on show, but now I have a favourite colour and just buy that one. They cost about $3 each, and last for a couple of weeks. If you are trying to decide about nipples, this could really help you. For me it has helped to prove that I don't really need to have another surgical procedure, and the nipples are good enough to prevent being noticed at the gym showers, so I am happy.
Regarding fat transfer, I had small one for a bit of a divert in my cleavage area on one breast. It helped a bit, but wasn't perfect. I have a flatish area on my first mastectomy implant reconstruction, and maybe if this ever needs replacing I might consider having it done again, but at the moment they look very normal in a bra, so I am leaving them alone.
Chris