There are a few things to consider when checking whether something constitutes plagiarism.
- Ethics: Are you presenting someone else's work as your own or using it without proper attribution?
In this case, I think you're well in the clear. You can rest comfortably knowing that you have created the information entirely on your own, and any similarities to other works are coincidental.
- Optics: Even if you've created the work entirely yourself, will others recognise that? Do you need to take steps to avoid the false suspicion of plagiarism?
The ethical question is the more pressing, but we can't discount the pragmatic reality. You knowing you've worked honestly won't be much help if someone gets it in their head that you've plagiarised something, so sometimes we might make sure to keep away from any false suspicion. In this case, an excellent question to ask is whether this information could be presented otherwise, or if this is simply the most reasonable/efficient method of doing so. Many people have used "2+3=5" or "In this paper, I will demonstrate that...", but that doesn't make the usage of such plagiarism. And, to extend the analogy, structuring a paper in a particular way will likely have been done before. (I'd be more surprised if it hadn't!) Structural similarities will, barring any other suspicions or dodgy scenarios, be dismissed as simply a necessary part of the process.
- Support: Is such a similar work actually a benefit to your work's credibility?
If you've done work and come up with a similar (or in fact the same) result as other people, that's likely a good thing! It not only gives your work a boost in credibility right off the bat, but it also helps the former work, as now it's being verified or corroborated.
So, in summary, I think that it would be ridiculous for anyone to claim plagiarism on your work, just because another paper about nearly the same subject had a very similar general structure. You seem to be in the clear both ethically and pragmatically.