While i hate to assume the worst there is a possibility the service you sought from fivver may have been some sort of scam if not just using bots to get you the numbers you were looking for
That said I dont think you should abandon your Ko-fi or Patreon if you feel capable of sustaining them even if you might not have a significant number of supporters right now. Continuing to take ink donations is fine as it's a slow build revenue that pays of with long term commitment even passively but more dedicated tip jars like Ko-fi can be useful since that's money you can quickly withdraw without having to reach a threshold like Tapas' required $25 for ad rev or ink support.
You do seem to have a fair amount of genuine subs so far tho looking through your pages info, so organic growth does seem to be happening through promo I'd imagine you're already doing here on the forums. If anything I'd say that would be a sign to try to expand to social media if you havent already. Using snippets of your comic, like interesting looking panels or pages, or more detailed illustrations if you have them can be easy access things to post and promote across the web. With that you can tell a bit about your story, giving engaging hooks for the overall story or little tidbits about upcoming chapters to build interest.
Beyond that for your support platforms like ko-fi and patreon you can consider setting up tiers for early access if you've got enough buffer to do so. so if you're already a few chapters or pages ahead you can let folks donate to access pages as they're finished or see wips or a peek at your process but whatever's most accessible for you in terms of time and amount of labor
If anything it's worth knowing and understanding that yours is not a unique issue. Lots of creators new and old will struggle to grow regardless of platform and even when you've got lots of subscribers or followers that may not always translate to financial earnings much less basic engagement. I've known folks with social media followings over 10k but barely even getting a few hundered out of that number to just hit the like button or retweet so that can be a double edged sword. The main thing is focusing on having fun sharing your story and doing what you're able to market your work but beyond that it's generally just a matter luck and timing. Sometimes you strike fire and get a big spike in growth and sometimes it's just a slow drip of sand adding to a pile but you can definitely pull it off.
All said best of luck and I hope some of the info I shared could be of help 
