Whether you have enough security depends a lot on what you normally do. Do you for instance install a lot of new software to try them out? Do you visit porn sites? Do you disable Windows Defender when a software asks for it? If you do these things, you should choose a 3rd party anti-malware - they generally score better at recognizing more malware than Windows Defender. And they have extra features like spotting phishing web sites, stopping ransomware and so on. Go to av-comparatives.com and read the test results. They are long winded, but av-comparatives does a good job at testing anti-malware products.
If on the other hand you don't try out new software often, then maybe an anti-executable would work for you. This class of protection scans your programs and only allow what you have currently installed to run - malware and new exe's will not run. Even if you don't install new software, mal;ware can still land on your doorstep when you surf to an infected web site. The major vendor in this space is Vooodooshield. When Vooodoo finds a new exe, it does a online reputation check and then shows you the result and asks you if really want it to run, There are others like Faronics's AntiExecutable. And the free Windows Defender Application Control Wizard; but you have to be very careful with this one, as some configuration mis-step can brick you PC. But there are users who have WDAC and not have malware for years.
