[Arald]

I don't see how I could use less. It's a small bulb and I use less than half of it at a time. It can't be more than 20mL each squirt.

feces is not stored in it its stored in the colon.

That is just plain not true. There is always feces in the rectum. When you have a bowel movement, what do you think happens to the rest of the feces that doesn't come out? It doesn't just float back upwards.

Edit: for the sake of dispelling this persistent myth, I looked for an academic source, as opposed to "sexologists". https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4125645/

Neil and Rampton[5] reported that stools are present in the rectum in 31% of normal subjects. Stools are also palpated by DRE in the lower rectum of healthy subjects and appear in the radiograms. [...] A small stool volume reaching the rectum from the sigmoid colon probably does not affect rectal distension or evoke the rectoanal inhibitory reflex (RAIR). In such case the stools accumulate in the rectum until they reach a big distending volume that initiates the RAIR.