Retention

I usually give myself an enema while sitting on the toilet. After emptying the 2qt bag, I cannot retain it for more than a minute. I'm looking for some advice

DON'T take the enema sitting on a toilet.

Lay on your back as you take and retain the enema.

Yes, you are fighting gravity if taking an enema on the toilet. I know one elderly woman who does them that way because of infermity, but she hangs the bag up high to increase the flow rate at least.

Taking an enema while sitting on the toilet is probably the safest way to take an enema if you ware worried about an accident, but it is the least effective position to assure a thorough filling of the bowel. Here you need to think gravity. The textbook recommended position is laying on your left side with right leg slightly drawn up and bent; but equally efficient, in my opinion, is laying on your back (my favorite position) or as I was required to do when younger, simply bend over the edge of the bathtub. As for the bending over the edge of the bathtub position, I have to say that I find it somewhat awkward for self administration and find laying on your back in the tub the easiest and safest (accidents are easier to clean up) position to take an enema. If you are laying on your back in the tub and use an inflatable Balloon nozzle or butt plug to hold your enema, I think you will find retention to be much easier.

I use a butt plug.

I agree, the toilet does not allow you to get the best result. laying down maybe with a towel or two under you for leakage, but it's the best experience