I hate to tell you this bro but, I think the dragon soul will never go away. Dragons existed once but now only exist in spiritual forms. You need that spirit in order to become a dragon. You can't get rid of it. Either it overwhelms you or you take control. I suggest you take control right now.
I have heard that many people rarely see their soul in the shape of a human. A half-dragon soul might have little to do with actual species and more to do with your personality. If your power comes from that view of yourself and your soul is changing as you as a person, your powers may be weakening and going in new directions. I recommend you meditate and do research on what magic feels right for you.
Also take a break from magic until the full moon. you might just be burned out
I`m not too sure if it will help but to my knowledge what you want to do is nearly impossible without first making said soul whole, and then either taming it(not sure if expression is correct), kicking it out(no guaranty you will keep any ability you may have) or making a deal/pact with it which can actually be best choice.
Feed it, give it energy allow him to go hunting(basically he will go and gather "free" energy from either dream realm, astral plain or ether of physical plane/material plane/our plane) while you sleep.
Also it will need to form mentally so talk to it try to teach it it will make things easier for two out of three options I proposed.