Hello tkargo. This definitely sounds like a blockage of some sort. Have you tried putting a finger in your stoma to feel what it might be. If it is poo, then it should be easy enough to release as you irrigate. Sometimes it is worth doing it in two stages. The first to get rid of the blockage and the second, to irrigate as normal. However, if it is a parastomal hernia, then Veejay's idea is a good one. I have a parastomal hernia so I made a similar device to his but dispensed with the cone and adapted an anal catheta to do the job. (There is a picture of my device on my profile if you are interested) I also found it useful to use a battery powered portable shower pump along with a 3 litre water container. ( which is a plastic cereal container - useful to store the equipment when the procedure is finished- and for travelling) The water under pressure helps to get the end of the tube past the hernia. However, there is a fair amount of splashback (prevented from going everywhere by a rubber washer on the tube rather than a cone). The advantages of this method is that I can push the tube in to about 6- 8 inches and past the hernia and any residual poo. The first few minutes is taken with expelling all the poo that wasn't fully expelled the night before. ( It gets pushed up and out alongside the tube, which is where the rubber stop is useful to direct it down the sleeve rather than further up the tube towards the top of the sleeve, Which I bend over and seal just in case.) I estimate that with all the backsplash, I probably get about 1.5 litres into the stoma past the hernia to do the job and this method has been okay for me for many years. However, I should mention that I was offered the opportuntity to have more surgery to fix it. Given all the problems other people have had with trying to fix hernias via the surgical route, I felt that I would hold off until it became impossible for me to irrigate using gadgetry. As with Veejay, I (nearly) always irrigate at the same time everyday - but I won't let irrigation interfere too much with other stuff I want to do, so I sometimes alter the timing and it doesn't seem to have too much of a detrimental effect.
I hope you find something to help with this problem. It is all part of the learning process we go through on our stomatic journeys. Let us know how you get on.