Has my macbook pro been hacked?

About one and a half week ago, I was looking on a site generated by a community (that was known to have successfully hacked another community they hated) with Chrome, then suddenly a popup window came out of nowhere and closed itself like 0.3 second later. I couldn't see which link it was from.

In the following few days, my mac has experienced the following:

1) turned on itself after I switched it off in the morning.

2) turned off itself when I did not.

3) when I tried to check my "Sharing" settings, it always lags for more than just minutes, forcing me to quit it using cmd+alt+escape. But then after I few attempts of opening Sharing settings again, it stopped lagging, and no sharing setting was checked at all.

4) mail app opens itself when I am certain I did not click on it and I did not see it moving up and down on the Dock

5) I had an unpaused youtube video on Chrome. I pushed the lid down completely for a number of minutes. Then I heard the youtube video starts playing itself even with the lid completely down. And this happened to me for the first time ever.

I have already scanned my entire mac with Sophos. I dragged everything in my "Machintosh HD", which included folders of "Applications", "Library", "System" & "Users", and also a single shortcut file called "User Information" to scan. Sophos found nothing at all. My mac is running the newest system version i.e. El Captain version. 10.11.6

All these suspicious things happened in a number of days after that popup and it just led me to think my mac is hacked, but not via "sharing" or "malware" (because I have not even downloaded anything from that quick popup. Unless malware can be installed via quick popup without me clicking on anything, but I am not a hacker and I dont know about java script hacks so I would not know.). Perhaps they hacked it via router settings? I just really dont know how advanced they can get. I have been researching on the internet/ forums/ youtube videos, but the more I am connected to the internet instead of just keeping my mac shut, the more time the hacker has to look through my. files.

Please. Help. Really. Ive done everything I can. Dont patronize Apple by saying "mac doesnt get hacked easily because it is safe/unlikely/few market/".