Below is our answer that we sent to you on February 13, 2019, Question #543635.
We are thrilled to hear that you realize that this is a very difficult area to try and grow a traditional lawn. Even better that you appreciate moss, which can be very lovely.
We do not have students that would be able to come to your property.
You/your landscaper will need to figure out the drainage issues, and may even consider a 'rain garden' for the lowest spots. These are areas that are planted with native plants that don't mind wet areas.
Here is more about that http://extension.umd.edu/watershed/rain-gardens
and a list of resources to explore for dealing with water issues and poor drainage.
This page in particular addresses poor infiltration and what you can do.
There are landscapers that are certified through the Chesapeake Bay Landscape Professional organization that may be helpful with what you have in mind there. You can search their site here: https://cblpro.org/
Here is a page from our website on moss. At the bottom is a link from Va Tech which offers information on growing moss gardens http://extension.umd.edu/hgic/topics/moss-your-landscape
Here are more options:
We suggest contacting the Rainscapes program through Montgomery County to see if they can offer any assistance. https://www.montgomerycountymd.gov/water/rainscapes/index.html
You also can contact your county soil conservation district (SCD) office. The SCD offices vary somewhat in the services and resources available to assist homeowners. In some cases they may perform a site visit and provide a written report that includes suggested actions.