I have "built" 3 homes. By that I mean 'I served as my own general contractor'. I initially wanted to do the work myself. After taking the local owner-built-home adult education course, I concluded that there was way too much work to make it practical.
After "building" my first house as my own general contractor I did some calculations and found that there was about 10 years of labor involved. That was with pro subcontractors.
As my own general contractor, it took about a year. I might be possible to do it in as little as 6 months, but that would be an intense grind.
I have known people who did much of the work themselves, but they still used some subcontractors and hired help. These houses often spent years with a finished exterior and severely limited finished living space. The rest of the interior was just empty space. There were treats of divorce along the way before it was eventually finished.
With finished walls and roof, it looks like you are nearly done. Not by a long shot. The most money and time spent is still ahead.
I strongly recommend serving as your own general contractor. You can save 20% to 30% and get the house you want not what someone thinks will sell lots of copies. Find an owner-builder course. I took the same course half a dozen times to keep focused and motivated. Believe me you will get enough opportunities to hammer some nails, lay some tile, install cabinets, etc. to satisfy yourself. Once you are done, you will know you built a house. Believe me. It's a lot of work and worry.
If you insist on doing it "yourself", try to find a design intended to be build in habitable stages. The saltbox design from America's early days is an example. The first stage was a very basic shed. When the opportunity arose, the next stage was a connected tall gable roofed structure. The shed became the kitchen. As the family grew and the opportunity arose, a second story or loft was built inside the second stage. You get the idea.
About multiple stories, figure a big cost increase.
Don't feel down about this post. Building your own house, no matter how it's done, will entail lots of ups and downs. This is only the first. You will get back up, and do it again and again. Once it's done, it's an awesome experience. For me it was always a bit of a surprise that I was done. You just keep your head down and pursue each task as it comes. Then finally your are done.
