Let me first put some general points that will help you decide:
Advantages of using Blogger.com ->
1. Easy platform to learn and use
2. You are already familiar to the environment
3. In-build SEO(search engine optimization), this helps your blog easy to discover
3. Lots of plug-ins and themes , no need to be a programmer
4. Great Up time
5. No fees, charges
6. In-build advertisement support in case you want to monetize your site.
The advantage you get with a personal domain is :=
1. More friendly url, you can keep it the way you like
2. Site authority -> that mean that if your blog becomes popular, your domain will be listed in top search results, but it gives you added advantage that any other link you recommend in your blog will be rated (as per your site authority) higher and will also be shown up at top search results.
3. More control over layout, design and advertisements you wish to put on on your site.
Now, since you already have a domain, if you wish to consider hosting on your own please consider the following points: =
1. You must be familiar with the platform you chose be it Wordpress, Joomla or any other cms. These are free platforms but require a decent amount of time learning and configuring.
2. You must take care of SEO else your may loose some or more traffic to your site
3. You must choose a hosting platform, like Go Daddy, Hostgator or any other, these are paid option. You may also try blogging using Github and Jekyll or any other static site generators. This may require spending some additional time.
4. If you decide to migrate your blog, please ensure that the old blog at blogger.com is now redirecting to your site, else you will loose some audience, also please use a 302 redirection or canonical meta tags to ensure Google or other search engine do not mark your site's content as duplicate.
5. Please try avoiding free hosting platforms as they generally generate spams and other malicious software to your site.
In short, it is okay to keep your existing setup,.