Well, you are a good artist. You've a distinct style which draws a lot from early 2000's web cartoons, it's full of life and personality. Everything looks solid, and proportionate in its stylisation. All told, it's very fun to look at.
What it isn't is a style which is currently trendy. Which may be part of the issue with numbers on socials like Twitter and Tumblr. It's up to you whether you want to pursue shifting your art style to pick up certain features of what's trendy at the moment; personally, I don't recommend that. You already have a distinct style with a lot of visual appeal, which many people search in vain for years for. Trends come and go. You may find, as tastes change, that your art hits a nostalgic niche in the years to come.
You're not doing badly numbers-wise on Tapas. (Says the newbie with 160 subs... but I figured being in the 10,000 mark on Tapas was pretty good, considering it's a smaller site than WEBTOON.) Plus, your comic is a lot saucier than the standard here, which works against it due to the audience demographics here. It's also in page format which, again, works against it.
What you could try is writing a comic in a different genre, to see if your style translates well into long-form stories and such. Those are more appealing to the kind of audience on Tapas and WEBTOON, which is younger and is predominantly female. An ecchi comic is a hard-sell to that audience, regardless of how lovely the art is.
(I also agree with everything @darthmongoose has to say, she posted while I was still typing, but she absolutely nailed what I was trying to get at. You have to adapt as times and tastes change. You'd have been enormously popular in the early 2000's, but this is now, and your work, good as it is, isn't what's popular.)
As for general illustration on other social media sites, that's an absolute crapshoot at the best of times. Those aren't the numbers you want to focus on. But if you do want success there, you need to take an honest appraisal of what styles do well on those sites, and incorporate those features into your own style. Both of those sites are all about trends, that's just how social media works, so adapting to that is key to success there.
I should add, when I say I don't recommend changing your style, I mean changing it whole-scale into something unrecognisable. But you could easily remove the ecchi elements without removing the sharp linework, watercolour/copic style colours and dynamism which define it. Your style, with fewer chibi elements and adapted to a more serious, long-form comic, could have some serious bite to it.