What you are doing is causing fluids to be retained in the area of the frenulum. There are groups of men who actually believe masturbating in a certain fashion, causing swelling to occur, will increase the lengths of their penises. There is no scientific evidence of lengthening occurring, but it does cause foreskins to lengthen. If your foreskin already has an overhang, you might not want to do what you've been doing. Swelling generally takes about 24 hours to subside.
I suppose young men attempt to retract and replace their foreskins during masturbation, thus applying some tension on the frenar band, and in time, loosening it to allow easy retraction. That makes sense, but it's a slow process. Some gain retraction by simply having intercourse.
Have you actually located your frenar band? How much overhang is there? Have you tried something like Q-tips or chop sticks? There are stainless chop sticks which won't bend while applying pressure.