I've been lucky enough to hit front page once. I usually get around ~40 upvotes when I post, a few hundred on a good day. Have made most viral twice, and I know of at least one other instance (I think it's the only one, but I can't technically be sure) when someone else made the front page by reposting one of my comics.
Imgur is usually looking for humor more than artwork (as far as webcomics go, at least. Imgur loves truly beautiful and unique artwork just as much as reposted memes), and if the joke isn't all that powerful of a punch line or is a common kind of overused joke, people can be brutal. Luck is also a huge factor - the same image may do wonderfully one day, but awful the next.
Looking at your post, your description may have turned people off a bit. You mention the fact that you are the main character, and people who don't know you might find that narcissistic. Plus, the facebook link might come across as self-serving. You will probably do better if you win them over BEFORE trying to advertise yourself - like replying to comments with a link if people ask if they can find you elsewhere.
The description also is important on imgur. You can try something a little more personal (my front page one had a description of "I started drawing a comic thing recently"), or just the title with "(OC)" afterward if you want to tactfully draw attention to the fact that it's your own work.
The image size and quality of your post also could be better. Some people may beat up on you for that.
Don't take it as a sign that your comics are "bad," though, if you get downvoted. It happens sometimes. You'll need to have thick skin and just keep experimenting until you get the hang of what they like. Imgur is a haven for everyone posting what they find funny, so as much as usersub might seem random and unfunny, you are competing with some of the best the internet has to offer if you want to make it past usersub. So, don't take it too hard if your post doesn't go too well. People love to downvote.