Hello, HK..
First of all, regarding your configuration:
1. You should add at least one on-demand scanner, like HitmanPro & MBAM.
2. You should add the following extensions to your browser: uBlock, WOT & HTTPS Everywhere
3. It's not stated, but if you don't have it, add CCleaner to clear your browsing activity.
Regarding 360, there have been some speculation, but only that. What you mentioned about a backdoor, it came from a chinese company (a competitor), and in China competitors act like that and say this or that about other companies. Its privacy policy is among the best, in my opinion. It seems like I'm defending them but that's because a product isn't bad, just because it's from a specific country. Google is not trustworthy for me, should I distrust every US product? Of course, I don't know what's goin' on in the background, but what I know is that it's a great product that can protect you better than others, free or paid.
Thanks for sharing!