Oh Cinder you boob, you've gone and burned yourself out. :v
So anyways, let me tell you a few things: First of all, when you say you aren't improving, that is complete and utter bollocks, i see a very significant improvement during your thread from start to end (especially during the drawabox arc). It's a very gradual process, often so gradual that you can't see the progress yourself before you compare the present to 4 years ago. I know i often find myself looking for "breakpoints" in my own gallery, only to be disappointed that i can't really find any. It hurts sometimes, it truly does, and i get why you feel like you do. You just gotta remember, feelings aren't always in tune with reality, and that you are your own harshest critic. It's a delicate fucking balance between being okay with what you do, while still realizing that you can always learn. If you consider everything you draw flawless, you won't improve, but if you think it's all trash, you'll be disheartened. Consider both what you did well and what could be improved, and at the same time, allow yourself to have fun. Draw silly things that make you laugh and smile, and even if you believe you've failed miserably, you can have a giggle at how badly you think it went. Dark humour is the saviour of many a dark situations. :v
I know i might be preaching to the choir here, but with how much joy drawing has brought me, it saddens me to see others get disheartened about it, especially when they've gotten so far. I get that you're probably burnt out right now, and it's totally okay to take breaks, however long they may be. I also get that i may have been... Less than diligent at commenting on your stuff, and for that i am sorry, but know that i'll be happy to see you get back to it, whenever that may be.