The short answer to whether you need to track analytics for your website is no, not in my opinion if you are the average psychotherapist, counselor, psychologist, social worker, solo practice ND, life coach or psychic.
I know that's tantamount to heresy. Folks who are in business to sell you SEO services (that cost hundreds and thousands of dollars) and others who are enamoured of statistics and measurements, will tell you that without keeping an eye on all the trackable components that your blogging and other online marketing efforts are wasted.
Let's be clear. If you like statistics and gain value from staying on top of them every week, it won't hurt you to track your analytics.
But if all those numbers create more overwhelm, anxiety, and confusion than claity, the sky will not collapse on your head if you spend your time writing a blog or creating an info product instead. You really don't have to be, or pay, a data junkie to have a website that attracts clients to your practice.
Tracking the number of clicks to your page on anxiety won't help you if the content on that page fails to make an emotional connection with the reader that motivates them to make an appointment with you.
Tracking which search engines are used in finding your site is interesting, and useful if you use that info to then pay for ads on those search engines. If you aren't doing Adwords or Bing Ads, the info is worthless.
Isn't There Anything Useful About Analytics?
Yes. Being able to see which pages your visitors arrive at and where they go before leaving your website, and how long they stay on each page, are perhaps the most useful features of an analytics program.
This information suggests that something about the visual design of the page either promotes or deters reading the content, and / or that visitors are immediately able to find what they are looking for. You can then intuit whether what you did well and what is presenting an obstacle for reading your marketing message, or engaging with your interactive features. You can intuit whether your niche focus is what people are looking for, or not.
What Do You Recommend?
I personally find the Google Analytics tool over-complicated to install and comprehend for my own needs, although I do have it installed for this website. I refer another tool, called Statcounter.com for easier data displays. And Statcounter now has a workaround solution for Google's refusal to provide keyword details. I like that they have been extremely responsive in addressing that problem that Google created.
Statcounter is free for sites that have less than 250,000 page loads per month, which is all that most therapists would need. And they have coding to add to your Wix website that is specifically configured for the Wix html5 requirements.
To add the Statcounter code to your Wix site, first get the code. Then open your Wix editor, and go to the Add tool to install html code.
Follow this path of clicks to do that: Add > Apps > html > settings > mode > html code.
Then like any other text box, you can move that box around your page and put it where you want.
Wix also has an app called Visitor Analytics that is easy to understand and installs with one click. I add it to every site I build because even the limited free version provides interesting and useful information.