If you’re planning a hospital birth, bring your own doula!!
I think we often underestimate the amount of paperwork (and everything else) that an L&D nurse has to get done for each mother and baby. This particular nurse used to be a doula, so you know that that is where her heart is — in being with a woman during labor. But it is many times simply impossible. If you do happen to have a nurse who is a doula to you during labor, be very grateful; but many nurses would love to be able to do that and just don’t have the time — perhaps it is because their particular hospital is set up in a way that will not allow them to do so (too many patients, too few nurses), or it may be that on this particular day/night, they’re swamped.
Since you cannot reliably plan on having a supportive nurse who is able to be there for you in the capacity of a doula, bring your own birth attendant. Because if a former doula cannot “do the doula stuff” as an L&D nurse, you can be pretty sure that other L&D nurses who have no doula training (and maybe little experience or even no desire to be supportive during labor) will likewise be unable to do so.
You do not necessarily need to have a professional doula (although that certainly wouldn’t hurt), as long as you have someone who will be a good and supportive labor attendant.
If you’re planning a home birth, a doula is probably going to be less necessary, because a midwife will be able to do a lot of those duties, or will have an assistant or doula as part of the “homebirth package” (at least, both of my midwives did). However, midwives are only human, and it wouldn’t be a bad idea to have another pair of hands. If you have a very long labor, or your midwife has another client due or in labor about the same time, or just to have somebody on hand to lend a hand or give your midwife a break, then a doula could be priceless. In my opinion, for a hospital birth, a doula should be mandatory.