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Where is it leaking from ?.
Try a larger diameter catheter? They’re usually numbered 12, 14, 16 etc. so it sounds like yours is either blocking (does it look cloudy at all?) or the urine can’t get down it fast enough so it leaks past the condom bit - which doesn’t seal well enough.
I take it you’re free-draining, in that your bladder is recovering so you’re not holding on to the urine then letting it go all at once as you would normally? This would put loads of pressure on what is basically a narrow hosepipe.