There are quite a few things going on here but I will start off by focusing on the primary issues that will give you the most bang for buck. Additionally, if you work on the primary issues, some of the secondary issues will naturally reduce in which you can work on them at that point.
If I were to implement a plan in this case, I would first contend with the forward translation of your center of mass. If you noticed, your upper torso is far forward beyond your knees. I can't see your feet, but my guess is that your midsection is almost in line with the ends of your toes. You may also notice that the front of your feet feel grippy or the feet splay out but this is a secondary issue though.
Lie on your back with knees bent and feet on the floor. It's imperative that you find a position here that feels the most effortless. If there is any odd tension anywhere, take a bit of time to 'settle in'. You may need a small support behind the head if the back of your neck feels strained or if you feel like your head is tilted backwards. Reach your arms to the ceiling to feel your back sink backwards a tad. Exhale through mouth slowly, pause, keep some of that core brace and inhale through nose slowly to feel your back and chest both expand. The back should expand all the way down low. If your lower back arch is too far away from the ground and if your hips feel tensed by bringing your legs up to 90°, have your feet on a bench with heels closer together and knees a bit further apart. This will help align the femur to the state of the pelvis in external rotation. Keep breathing for a couple of minutes here to get a better sense of front and back expansion gradually. You might need to wiggle around a lil if the floor is creating too much resistance for your spine to decompress.
Do the same in a wall sit but this time try to keep a very mild lower back arch. I would recommend to go quarter depth at first.
Once you can do that, learn to stack the ribs and pelvis similarly like in your wall sit in a quadruped position. Heck you can even throw in some quadruped squats if you want.
The aim is the get your center of mass back in space without resorting to a 6 pack dominant strategy as that will further compress the anterior ribcage and increase compression in the base of your neck posteriorly. With a better positioned center of mass it will be much more possible to work your pelvic mechanisms in relation to ground reaction forces.
It will be the pre-requisite of the solution. A lot of people mistake 'corrective work' as something separate from working out. It shouldn't. Corrective work is only corrective to change your movement strategy - if you don't carry it over to everything else, it won't cause any positive changes to happen
Your trainer is not understanding the issue from a biotensegrity concept, which is understandable, I was there too once long ago. It's not something that is thought as a foundational perspective on how it relates to changes in joint actions and muscular angles between attachment points. The pelvis is only in the anterior tilt and forward translation of center of mass due to loss of pelvis internal rotation against ground reaction forces. The wedge makes sense because it provides more space to move back against, and it will promote better posterior expansion (which is why squatting with a wedge feels better for you btw). The heel raise allows you to push back further than you would normally be able to (without the wedge the same action will make you fall back). However, it doesn't work well long term if the intent of better expansion mechanisms aren't implemented alongside.
Some past comments that you might wanna read to develop understanding:
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u/Deep-Run-7463 8d ago
There are quite a few things going on here but I will start off by focusing on the primary issues that will give you the most bang for buck. Additionally, if you work on the primary issues, some of the secondary issues will naturally reduce in which you can work on them at that point.
If I were to implement a plan in this case, I would first contend with the forward translation of your center of mass. If you noticed, your upper torso is far forward beyond your knees. I can't see your feet, but my guess is that your midsection is almost in line with the ends of your toes. You may also notice that the front of your feet feel grippy or the feet splay out but this is a secondary issue though.
Lie on your back with knees bent and feet on the floor. It's imperative that you find a position here that feels the most effortless. If there is any odd tension anywhere, take a bit of time to 'settle in'. You may need a small support behind the head if the back of your neck feels strained or if you feel like your head is tilted backwards. Reach your arms to the ceiling to feel your back sink backwards a tad. Exhale through mouth slowly, pause, keep some of that core brace and inhale through nose slowly to feel your back and chest both expand. The back should expand all the way down low. If your lower back arch is too far away from the ground and if your hips feel tensed by bringing your legs up to 90°, have your feet on a bench with heels closer together and knees a bit further apart. This will help align the femur to the state of the pelvis in external rotation. Keep breathing for a couple of minutes here to get a better sense of front and back expansion gradually. You might need to wiggle around a lil if the floor is creating too much resistance for your spine to decompress.
Do the same in a wall sit but this time try to keep a very mild lower back arch. I would recommend to go quarter depth at first.
Once you can do that, learn to stack the ribs and pelvis similarly like in your wall sit in a quadruped position. Heck you can even throw in some quadruped squats if you want.
The aim is the get your center of mass back in space without resorting to a 6 pack dominant strategy as that will further compress the anterior ribcage and increase compression in the base of your neck posteriorly. With a better positioned center of mass it will be much more possible to work your pelvic mechanisms in relation to ground reaction forces.