Maybe the silicone flanges are the problem? They’re painful for me and so I never use them, might have thrown them away.
It could also be you don’t have enough skin to facilitate the expansion, so it’s causing excessive pulling on that spot.
It could also be that you have a low body fat percentage. More of a fat pad at the base of the penis seems to be beneficial for pumping in multiple areas: better seal, less skin stretching on the penis itself. It can really hurt when the pump is pressing directly on the pelvic bone.
Might also be a lube issue not allowing the skin to slide if it needs to.
I use a lube made with glycerin, distilled water, l-arginine or very small amount of guar gum, and sometimes a little bit of menthol. It makes cleaning the tube much easier than when using oil lube, it’s less likely to be colonized by bacteria or fungus because the glycerin, and it doesn’t seem to go rancid like cooking oil. Glycerin irritates some people’s skin, but it’s fine on mine. If you’re the type to not clean out your tube regularly, it might be a good idea. I left a tube I wasn’t using dirty with oil for a few days and when I got around to cleaning it I could see very clear mold mycelium spreading inside the tube.
Starting: 7"bplx5.2" 2017 (shrunk from disuse)(originally 8"bplx4.5", gained to 9"bplx6")
Current: 9.0"bplx6.125" 2020
Goal: 11.5"bplx7" 2021.