Hi Brooke - this is probably just due to a version update on Chrome, so unfortunately this method may not work as well at this point.
This is due to personalized search: Google tweaking search results on an individual basis due to user's internet history. This might be great for the average search engine user, but it is of zero help when you are trying to manually check your rankings. With a simple change in your Chrome browser settings you can permanently get rid of this headache and start seeing search results as they should be - depersonalized.
Note: this only works if you are using the tool bar in the Chrome browser.
Step 1: finding the search engine control panel in Chrome
In the upper right hand corner of your chrome browser window you will see a wrench icon. Click on that icon and select "Options" in the drop down menu.
In the new page that pops up select the basics tab. You will see a search section and a button that reads, "Manage Search Engines," click on this button and go to the next prompt.
Step 2: Creating a Custom Search Engine in Chrome
At the bottom of all the possible search engines you can choose for Chrome to use in its toolbar there is an option for "add a new search engine."
Name the search engine something like, "Google Depersonalized Search" leave the keyword field blank (it will auto populate) and in the field that reads "URL with % in place of query" input this URL:
Then select this newly created search engine as your default in Chrome.
This will permanently depersonalize your results in Chrome and you will no longer have to worry about your internet history skewing your search results when you are checking to see where your site ranks.