I agree with the majority of comments above. To add a few of my own:

It seems men take longer to learn steps than women. Exactly why is unclear, but men seem to have a much harder time in the beginning - maybe because we need to worry about the step(s), leading the step(s), and floorcraft.

17 lessons isn't much time. Maybe it would be if you concentrated on a single dance, but I'm guessing you did a "variety pack". It takes time to get the steps burned into muscle memory.

When I was a newbie, I found it most helpful to take Bronze group classes and then follow up with a private lesson to clarify, review and work on technique. Even after 5 years of dance lessons, my wife and I take Silver group classes to get the basic syllabus and then refine what we've learned with private lessons. We've also found that semi-privates are a good compromise between group craziness and (expensive) privates. (Our semi-privates usually have 3-4 couples and we focus on technique).

Lastly, practice, practice and practice more.

And here's a true story:

When I started taking ballroom classes, I was so bad that even some assistant dance instructors tried to avoid dancing with me. Last month, my wife and I competed in International Standard at a National Qualifying Event and did reasonably well in our division. So it's true that there is a light at the end of the dance tunnel.