For a handicap bathroom, go to the Americans with Disabilities Act (ADA) site. It has specific measurements and requirements for construction.

You will need to contact an architect to design your other rooms. Go to Houzz Professionals. Scroll down to Architect. Enter your zip code in the search box with the tiny magnifying glass. Look at the work of the architects in your area. Contact one or more of them directly for a consultation.

Here is some more information.
Houzz
1.) Go to Houzz Ideabooks. Enter "Universal Design" in the search box. Be sure to use quotation marks.
2.) Go to Houzz.com/Handicap-accessible
3.) Go to Houzz Design Dilemma and enter "handicapped" in the search box.

Universal Design
1.) www.universaldesignstyle.com
2.) www.schaefferconstruction.com specializes in Universal Design

Handicap Access
1.) The Americans with Disabilities Act (ADA) site. It has specific dimensions for wheelchair turning radius, placement of grab bars, everything.
www.ada.gov/adast94.pdf
www.ada.gov/

You can look for CAPS (Certified Aging in Place Specialist) certified professionals in your area by searching here on Houzz or by going to the NAHB.org website. These folks can help with universal design and accessibility issues throughout the home and can help with design in most cases.

Here is a link to a prior bathroom discussion that might be helpful. https://www.houzz.com/discussions/bathroom-remodel-dsvw-vd~467406