Quite common for newer taxidermists to take on such a tough pose. They often have high hopes that they can pull off such a difficult pose, and they are skipping past the fundamentals. You must first learn the basics before leaping head first into this. In other words the preening, neck turned one legged standing mount is difficult to pull off for a professional, making it that much harder for a novice. You took on a lot. My suggestion would be to look at references, try a flying mount which may be easier, and study anatomy. Balance is certainly off, and it looks like you need to work on your sewing, balance, and finish work. It could look smoother on the underside of the bird. I try to let people know that there are beautiful pieces out there with some very skilled taxidermists who make this look easy. It is not easy. These high level taxidermists didn't start at the top. They took lessons, learned from their failures, improved, studied references, learned anatomy, and basically started with the basics. Learn how to skin, flesh, wash, dry, sew, and wire. Do a bunch of birds that will be less than stellar, and take notes on what you did wrong. Fix those things one step at a time. Don't fix three things at once. Fix one thing, until you've fixed it. Ask questions. I'm never satisfied. Probably never will? I need to fix some things, and I know what they are. Once again, these guys who are in the top tier who make it look easy took their lumps too. I don't think bird taxidermy is easy. I think it is super fun, and a great hobby, but never easy.
I give you an attaboy for showing your work. That takes balls. It is however the first step in getting better. If you can take a critique and accept the fact it may have come up short, but are willing to learn from it. You are way ahead of the curve. I can't do it. Good for you!