A lot of my early growth came from folks that I met here on the forums. A little self advertising here, a lot of participation in all sorts of threads there, and the common practice of adding a link to your series or profile in your "About Me" section of your forum profile (it doesn't look like your series/profile is linked in yours yet. To see what I mean, click my name and see the little blurb that pops up with my link at the end of it).
After my series hit its stride and had some momentum going it honestly just seemed like a lot of the readers I picked up discovered me either in the "Fresh" or "Trending" section of the website/app. Many of the subscribers that I don't recognize from around the forums would show up on upload days presumably while I was still in the Fresh section 
One thing that I've noticed that doesn't work so well for Tapas (for me at least!) is trying to get other people here from external advertising... a lot of folks who don't already have a Tapas account seem to be disinterested in making one. For example I have some irl friends who have seen my posts on social media and read my comic, but who never subscribed because they would just click over to the site to catch up when they'd see my posts every so often
even among more avid webcomic readers, I've met and talked to a lot of people who only use the Webtoons app and so I usually just point them to my mirror on that site rather than try to coerce them to download an app they don't want.
Despite the above I consistently had a higher number of readers on Tapas than Webtoons, for my first comic at least~