Lean back more. You'll feel like you are super far back but you aren't. You can slowly as you get stronger start sitting upright again.
Do NOT grip with knees, tense up shoulders, pull legs up.
Melt into your horse's movement
Every beat, use your ankles as shock absorption and think drop, drop, drop
Practice by rising 1, sitting 2. Then rising 1, sitting 3 then 4 then 5 etc until you have got the feel and have build strength.
Try sitting at the beginning of the trot. When you go from walk to trot. Sitting from rising is much more difficult.
10 000 hours. Practice practice practice. Maybe get your horse to slow the trot down and the more engaged and relaxed your horse's back is, the more comfortable and easy the trot would be to sit. Think of your horse's back like rubber; soft and moldable with a powerhouse engine underneath motoring upwards (hind quarters) visualization works.
If you grip with your knees more it seems to stabilise your position.
I had the same exact problem but my trainer recommended to me that I allow my seat to move back a forth a bit. I think about it every time I do a sitting trot and it really helps
Try not to brace in your stirrups....just let ur foot float on them. When you’re stiff and tense you will bounce. Try to image melting around your horse and follow the motion with your hips....Just remember to keep your hands still and upper body still.
Thank you! ill try this next time im at the barn.
Imagine bringing your pubic bones toward your chin whenever you bounce. Basically a sitting trot is like doing crunches. Try it bareback first if you can and get a feel and then get in a saddle. Hope this helps!
Make sure you are not stiff at all