Hey Mel! Glad to see you jump in here.
Deviantart is not a very good place to find new readers. DA was a great place for gaining visibility years ago, but these days most people are only looking for fan pieces. If you participate in DA groups you can push your discoverability across the site up a bit, but there's a lot of luck involved too there. However, I have noticed that after joining 3-5 very active ones and posting regularly that my exposure/fave quotient has gone up.
Books at conventions -- are you currently doing any? I've talked to a few folks who are indie guys in similar genres at places like Dragoncon and small cons - and people are more likely to pick up a book (within a price range and decent sales pitch) and do something with it than take a card. My business card/bookmark conversion to readers is low. So I started just giving bookmarks away because they're just part of luring a person to the table to talk.
Advertising to the webcomic audience - could work, but it has to be done carefully. I would emphasize art more heavily in your layout and use them often when you can.
But if you try to capture some part of that audience, there is a certain look/standard that has become quite popular (maybe due to the templates all running similar in style/layout to maximize ads). This tends to mean a certain type of navigation that folks are accustomed to.
If you do decide to attempt to capture the webcomics route, try to find some advertising partners with a decent amount of volume in your genre (e.g., via low-cost ad sites like PRoject Wonderful).
In terms of finding readership within the serial community, make sure you also listed at Muses Success. (I think EpiGuide is more for of a different style, but you'll have to ask the maintainer.) Also for your serial in particular, look at Comic-Rocket.com since you consistently use illustrations with your serial. They've allowed me to list on the basis of my early chapters.
Participate in social media more like Tumblr and Twitter. The art folks have long left DA and seem to be doing a lot more networking and curating via Tumblr. Twitter is useful for me to chat with other artists and the occasional author .
Lastly look to other means for distributing your work, whether it be e-book, sites like Wattpad, and any methods that are not reliant on the traffic going to your website.
Regarding the many volumes you have. I was surprised when I picked up your current updating one that I didn't really need to have finished everything prior. There could be a misconception with series that you HAVE to start with the first and tbh, that one is harder to get into than your current one. The narration in your latest volume sticks more with one character (and one who I honestly relate to better). I'm all caught up with that one, while I lag on the others. I can't really explain fully what's happening but I think the first person narrative is at times a double-edged sword. Your Anabelle is more like the reader whereas Tom, Lucien, and others are not. If I were you, I might build a small campaign in the 'Romance'/'paranormal' category around Volume 4. Volume 1... not sure yet. That feels a little bit more like straight out 'magic' and intended less so for a female reader. It probably markets differently...
That's a lot of stuff . Sorry for the text-vomit (as I'm trying to work and write this post at the same time). Since I frequent most of the same venues you do, happy to commiserate if you ever want offline. But yeah - deviantart is dead. I encourage you to go Tumblr and stick with it. Twitter is good for networking too as well as keeping track of things going on the web.
Also, for you, would suggest you look at Tokyo Demons by Lianne Sentar to see how she's combining illustrations with text and also how she's targeting advertising. Her niche is not the same as yours, but what she has done is pretty interesting.