Hi dear
In this design, I have tried to make the most changes with the least cost.
Bright colors have been used to enlarge the space.
The heights are designed according to the standards.
I have suggested a laundry space above the bathroom.
Several storage spaces, including under the stairs, are designed to accommodate guest equipment.
A space for entertainment and games is also designed.
The sitting window is also designed according to your description.
I hope you enjoy this design