From what I hear, Patreon would definitely be the best for that sort thing. It can limit the number of folks that get to your higher-resolutions, while still satisfying everyone to see what you create. And more so, a fairly noticeable watermark never hurt when posting them publicly. (They can be ‘distracting’ for some folks, yes, but it would be completely for good reason.)

However.. I’d still think that you’d have to be careful. Patreon does limit to only those that pay you for your work, but anyone could save those works (I’m likely assuming), so the possibility of someone posting/sharing your work somewhere is still there. 

There’s definitely some risk everywhere to posting your work online, but I’d say go for Patreon if you feel you need to! It really could limit the number of folks that get the privilege of seeing the full size of your work to a more 'comfortable’ quantity. <:)

I’m really sorry you have to deal with this as well, Niro. Trust me when I say that your work is inspiring and admirable. You’re got great style and construction with your pieces. But that does not give others freedom to simply claim it as their own, much less repost it (whether or not they know that you don’t approve of that). I hope this dies down for you (and heck, many others) soon! <3