River, lake, saltwater? Are you tall, short, wading, fishing from shore? Is that rod full flexing or fast action? Are you loading the rod down into the bottom section?
A 500 to 550 grain window strikes me as closer to a heavy 7 weight or a 7/8 weight rod, not a 9 wt. If it is really a "9 wt", try a 600+ grain head.
Almost 14 foot rod, rated 9 wt...... That T-14 tip should be closer to 15 feet long.
Stop fishing and go practising. Learn how to throw a 15 foot sinking type III tip before playing with the T-14 as that will cut down your learning time. Considerably.
Add a metre-plus long leader and add a hookless fly or yarn. Otherwise, cracking the whip will occur often.
For this rig, I would avoid classic spey casts and initially focus on sustained anchor casts -- Snap-T, Circle-C, Perry Poke -- they are all roughly the same cast.
The hang distance can be important. If standing on the edge on the water, use a long hang distance. As you wade deeper, shorten that distance. If taller, use a long hang distance, if shorter, use a shorter hang distance. For most practice, stand on shore or a low-lying dock or wade ankle-deep at the most.
Watch the macho power drive. You are not driving T-rails into the ground with a sledge hammer. With a well designed, full flexing rod, this should be easy and not physically demanding. The same goes for fast action rods except sharper timing and overall better technique are required.
Slow everything done and initially focus on a shorter, more compact casting stroke. Teach yourself to observe your D-loop formation and the line stick. Some beginners experience tremendous difficulty doing this.
The D-loop formation should be smooth. The rod should not dip and D-loop formation should start to load the road for the forward cast before the forward cast casting stroke begins.
Line slack between D-loop formation and the forward casting stroke can kill the cast and should be avoided. Similar to single hand fly rod casting, keep the upper hand wrist relatively rigid.
How is your cack-handed casting? When I started out I was a much better cack-handed caster because my left shoulder stopped the rod from going too far back.
I initially corrected some of my regular casting faults by bringing my hands into the 'box', i.e., by keeping the hands close to the body. That way my upper hand forearm would jam up against my bicep and prevent the rod from going too far back and/or prevent the rod tip from dropping. Both errors risk introducing slack into the line just before the forward cast stroke.
With work and patience, you should be able to nail this down.
Science is not common sense. Much of it is devoted to a systematic documentation of what we do not know and understand.