It’s rather difficult to define, But from what you have said, there seemesto be a tightening of the fundiform ligament rather than the suspensory . So can I suggest you try to locate the fun lig by pulling your dick down at the front, (not from the rear) first you will feel the suspensory lig at the top. Then as you pull to the right you will find the Fundiform ligament at the left side. There is no muscle in your penis. So it seem as if it is the fun lig that needs the stretch if that is possible, and that is the one you should adjust your grip to concentrate on.
The idea here is to pull your body away from your grip on your dick so its just a case of pulling your lower stomach in so as to ‘flatten’ it You probably have a fairly flat stomach anyway this just pulls it in further pulling to the right just puts the load on the lower lig. So ‘sucking’ it in is what is wanted You don’t need to pull the muscle in front of your anus but it doesn’t matter if you do
Try to get your grip nearer to the base of your unit then you will be putting pressure on the part of the lig you want to reshape. Although there shouldn’t be a curving problem as you are really pulling in a straight line as it were, and not bending your dick but pulling it at an angle. Inevitably you will be putting some pull on the suspensory lig, but that is the way your dick is put together
In a sense you are in fact stretching one side of your dick. So you must expect any ‘gains’ will take the same sort of time scale as a normal stretching of the whole dick
As it is only one side it might happen sooner but you will have to be patient.
Hope that helps