It sounds like you are doing what you can...and thats all you can do...that and learn about it.
Lots of nasty things can get in there ....kinda like roaches or ants hiding behind other things...eewww!
Like I said...I learned most of this the hard way in the last 12 or 13 yrs...
There is a site online to get all the security info you need....and run tests to see if your pc is safe...click on the shields up and look around at those tests.. I've been going there and using it for years....and its free.

Shields Up       For anyone who wants to check it out.

 

“For those who believe, no proof is necessary. For those who don't believe, no proof is possible.”

[Stuart Chase]