I think part of your issue lies in this picture:

I can find a picture of Ken in a similar position:

While I'd have thought the disc is too far away from your chest, you can see that he appears to have the disc about the same distance away. But he also seems to be more weight forward as well.
You might try out a different disc, something like a valk in a 16xg range. Something you can hyzerflip for some additional distance instead of those dead flat flights. It's harder to push an overstable disc out far dead flat vs flipping an slightly more understable disc up and over and taking advantage of the glide. When I watch you throw, it looks pretty effortless, but when you look at your face, it looks like you're really throwing hard. One of the things you're missing I suspect you just don't have - arm speed. I do believe you could still go with later acceleration and get more distance. It would mean just sort of bending your elbow and then pivoting your shoulders faster and then letting that arm eject the disc later. The down side is that it's going to mess with your timing a lot.
Have you tried throwing anhyzer for distance? That might yield you the 25' you're looking for, too.
The one thing I do believe you can do is pull closer to the chest and accelerate later.
Good luck!