So, earlier on reddit I saw this picture that was a scan of someone's bowels that had been constipated for a while, and as a result had 4 kilos of stool in them!

Anyways, on the comments someone said that being constipated isn't necessarily not going or rarely going, but just not pooping enough and that is how stuff like this happens. Now I am worried that I am not pooping enough, and that I am going to end up being full of crap, literally!

How do I know if I am pooping enough? My stools have been soft and have been passing with no problem... is that a good sign that things are moving alright down there?

In my experience, it should be, and at the slighest sign of constipation i take a bit of my miralax or colace.
To me, having 2-3 soft bms a day is perfect as long as they hurt less and not more id say youre doing things right.
Magnesium 500mg at night works wonders to relax muscles and makes nice soft stools.
Chances are if you have 4 lbs of poo in you, you would know it.

And as for your question, they are soft... Passing with no problem... This is beautiful as long as its comfortable for you. If you start to feel really bloated and full, and start losing appetite, then id worry