To overcome bedwetting, two things need to occur (generally speaking). First, the child must develop the hormone that signals the kidneys to slow urine production. Without that hormone, the child produces too much urine to stay dry. Second, the child needs to learn to awaken to the sensations of a full bladder.
If your dd has always produced a lot of urine overnight, then she's probably not yet developed the hormone necessary to stay dry at night. If your dd wets less than she used to and/or has occasional dry nights, then she's probably ready to start training her body to awaken to a full bladder by limiting fluids before bed and taking her to the toilet once during the night.
FYI, most doctors don't consider bedwetting much of an issue until a child is 7-8yo. Even then there's not a lot the doctors can do except perform an exam to make sure there's no physical cause for the problem (infections, constipation, etc). Some children just take longer to develop the hormone to slow urine production at night.
There is a synthetic version of the hormone available as a prescription drug that some doctors will prescribe for children. It used to be available as a nasal spray, but the FDA discontinued their authorization of it for bedwetting purposes since several children were having problems with it (seizures? I can't remember). The meds are still available in pill form. The meds are just a bandaid until the body develops the hormone on its own. Some people just use meds for sleepovers (assuming they've determined that the meds help).
The American Academy of Pediatrics has a great book called "Waking Up Dry: A Guide to Help Children Overcome Bedwettting," by Howard J. Bennett, MD, FAAP. You can see if your local library has it.
It explains on both a kid level and an adult level various reasons why bedwetting occurs and methods for overcoming it. It gives info about how many children are still bedwetters, how to deal with sleepovers, what medications are available, etc. It's geared not only toward solving the problem, but making the child part of the solution and helping the child not feel badly about being a bedwetter. It even has jokes throughout it.