There is no way around it: in 2015, Google rankings are going to fluctuate. On the same token, while it may seem as though Google rankings are fluctuating, it may be that you are the one that is doing the fluctuating. What do we mean by this? Well, for the last few years, Google has been working towards “personalized search results” meaning they try to tailor the results to your liking, rather than showing the same results to everyone.
In addition to personalized search results, there are many other factors at play. If you Google “best web design company Delray Beach” you may get a completely different listing than someone who searches for that exact phrase in another location. Google takes many different factors into account including: your past search history, who you are, what account you are logged in under, your location, your browser history, and many more.
This is one of the reasons why your rankings are fluctuating. Also remember, there are normally 10 results on every SERP (search engine results page). That means there are 10 people fighting for that #1 position. In many cases each website has a dedicated SEO company fighting just as hard as you are, so your rankings might be fluctuating because your competitors might be influencing the SERPs pushing your website up, or down.