Y’all helped me figure out what shower valve I had. I bought a new trim kit to update the look of the bathroom as the valve was still fine. Now, as you can see in the photo, the handle isn’t big enough to surround the whole length (please forgive me for not knowing the name of the part) of the part of the faucet that sticks out of the wall. I wish this was just a cosmetic issue, but it isn’t. When I turn the water on, barely any comes out. Can anyone tell me what kind of handle I need to fix the issue?

tl:dr - smooth brain first time homeowner bought a shower handle that’s too small. Pls help. derpy handle