Trouble stretching beyond 17 mm

[superskeet1]

As the title says, a few years back I embarked on the journey to stretch my urethra to accommodate 20 mm (what I consider conquering a certain mm, to me, is getting it past the tight "ring" just after the glans) and so far I've ended up achieving 17 mm, but lately no matter what I do it seems I just can't get past this obstacle and I have now been stuck at 17 mm for over 6 months. No matter how much I stretch I always feel like I stay at the same level of tightness inside. The length of the meatus is not the limiter nor is it the size of my dick in itself as I've got a big glans and my shaft is 5.5 - 6 inches of girth erect, therefore I don't quite believe I've hit my "peak stretch", whatever that might mean because I know someone packing 4.5 inches of girth who managed 25 mm.

In short I'm looking for tips on how those that are at 18+ mm achieved their level of stretch because I feel like I'm doing something wrong with my routine.

[NuderThanNude]

Performing a meatotomy will help to remove the restriction inside the glans. However there seems to be a limit as to how much the urethra (especially in the glans) will stretch. My experience has been that after that point you need to make small tears instead of actually stretching the tissue by inserting larger and larger objects.

[derlongus]

I also thought a meatotomy would give me directly more room.
After cutting I have found, that the first restriction is gone now, but deeper down there is a second one.
So going for a subincision would solve that the quick way.
Otherwise train with pain....
I decided to go the training way for the moment