Renderings of front & Back of house
And ground level area with garage under the house

And ground level area with garage

Layout the furniture to scale on the plan to make sure there is enough space to maneuver comfortably. I think you will find things are tight. You may want to contact someone local that have experience with what you want to achieve.

Mark: Thank you I will!

Check the clearance for maneuverability in front of the elevator as well. It looks a little tight if a wheelchair is in use (or a possibility in future).

Maltby: thank you! How much clearance would be required
My husband needs a wheelchair

Mark: an elevator company will do the install. Could you share more info on what troubles might be encountered with this?
Now I'm a bit worried :(

I know that room is tight (although much more than our former bungalow). It is a shore home so we do get a lot of company. We were trying to fit in as many bedrooms and baths as we could.
How do I figure out if furniture will fit?
Is there a program or app?

The elevator company will install their equipment in the shaft constructed by your builder. The shaft must be constructed to meet the elevator companies specifications. The elevator company should be able to provide whoever drew up your plans with design criteria and details for the elevator to function properly. Be sure you let the builder know that this house is to be used by someone in a wheelchair. It is hard to tell, but it looks like by the shaft shown on your drawing that the interior of the elevator may not be large enough for a wheelchair.

desmad, I don't know what's required where you are, but in Canada a 5 foot radius is considered the standard for easily maneuvering a wheelchair. So if you had 5 feet clear in front of the door to the elevator, you'd have loads of room.