I can't stress what @lexvil said about trimming the catheter down. I do the same thing, but I've never seen that mentioned on here. My barbs to the quick connect are way shorter than the outlet on the catheter, so I have to trim a good 1/2" or so. The 1st time I did it (and if I've forgotten) it tends to kink more and that's unpleasant and somewhat bad for you as you can get a uti (although I haven't had one yet).
Just to make sure I understand this, you mean on the catheter side it's too long and you trim a little? Also the catheter does go over the barbed quick connect fitting barbs or inside that small barbed fitting? I would assume the catheter stretches over the barbed quick connect fitting.