Put in your lot size, home size and where you live, and see what the rules in your jurisdiction would allow. Then, if it looks worth it, I will come and check it properly for free.
Fill in what you know about your property and I'll show you what the rules where you live would allow.
Whatever this page tells you, it is working from numbers typed into a form. A visit settles the things that actually decide it: where the utilities run, what the setbacks leave you, how access works, and what your local planning department is approving right now.
You get a straight answer on whether it is worth building, what it would cost on your lot, and what the finished unit would be worth. No charge, and no obligation.
Based on the details you confirmed, there appears to be room to work with.
Standard designs from A+ Construction & Remodeling. Which one actually fits depends on the site.