I honestly wish I knew what to tell you, Janice, but I will speak from my own realm of experience as much as I can.
I've never used the "Self-Destructing Cookies" extension, but I have heard many good things about it, and would try it out except I'm not sure if it will break my logins during a given browsing session or not (I log into Gmail each day to check my e-mails & Facebook and Twitter to stay in touch w/friends among other sites). It would also more than likely necessitate an upgrade to a newer Firefox version, which I'm not opposed to doing but don't want to do unless there is a good reason.
It's just a theory on my part, but I'd presume that Google's ability to track you could be correlated with whatever you are using as your default search engine. It's possible that swapping Google for DuckDuckGo (or whatever alternative search engine you prefer) may at least partially thwart Google's ability to track you (as an extra security measure, you could go into the options menu and remove Google from your list of available/accessible search engines). Regularly cleaning/clearing out your cache is also helpful.
Another possibility is, as I mentioned earlier, to downgrade to the oldest version of Firefox still capable of supporting all of your addons (the last version of Firefox before it started turning into a Chrome clone was 28.0, but 24.8.1ESR is also recommended if you want something slightly more up-to-date as far as security). In general, the older a browser it is, the harder it becomes for sites like Google to pull their tracking BS that they are so keen on doing nowadays. Most people would scoff at even the notion of using a browser like Netscape 3.x/4.x for ANYTHING these days, but believe it or not it's pretty much ironclad as far as security. With a good proxy (I recommend proxycrime.com or fastusaproxy.com), JavaScript/cookies/CSS turned off, & regular cache cleaning it can still be used to navigate most websites, and is all but impervious to tracking and modern-day malicious scripts. I tried it out for a while and was quite impressed--there are a few things I can't do with it (like checking e-mails or using online translator services), but having another browser on hand to pick up the slack solves that problem. Netscape is my #1 choice for Windows 3.1 users.
Despite its flaws, Firefox and other Gecko derivatives are my most highly recommended browsing choices for Windows XP users. Based on my own experiences, Firefox 1.0.8 (released in April 2006, though the engine itself dates back to November 2004) is quite possibly the oldest reliable browser one can use in 2018--it has the tabbed interface which IE6 lacked (even if you use something like SlimBrowser, you're still tethered by the Trident engine's limitations, meaning that sites that don't render as you like them to in IE6 will render no better in SlimBrowser), supports a lot of sites that several-years-newer versions of Opera have problems with (for example, logging into my Gmail account is seamless in Firefox 1, whereas even with Opera 10.10 [released in Nov. 2009!!] there are constant 'Stale Request' errors; this was fixed starting with Opera 10.5x, however, but GenYouTube.com only starts to work properly in Opera with version 11 [the first of its kind of which was released in late 2010]), and is more lightweight in RAM use than 2.x/3.x. Not to mention its astonishing versatility as far as OS compatibility...Firefox 1 (and 1.5) will work on nearly any OS you throw at it! There are a few conveniences I'd gotten used to in newer versions that FF1 doesn't have but for all the basic stuff it's still rock-solid.