This is My proposal for Your house based on Your desires and construction limits. By demolishing a few non - bearing interior walls on the ground story the plan becomes an open living space with a built in fireplace / kitchen -with food preparation part in enclosed glas box- / dining / library area, with two symmetrical wings, one dedicated to Your son's needs, while the other represents Your Master Bedroom with additional bathroom & wardrobe spaces. The glass cube added to Your open living zone represents a greenhouse attached to the inner balcony, while the other half leads to an open patio which connects the house to the garden. The guest room and gym are situated on the first story.
Best regards!