I tried squatting this morning as suggested, as well as waiting a little longer on the can to see if anything came of it. I did pass more stool, each time having kind of a double-movement of my bowels separated by a few minutes. I may have even had that little squirt of pee at the end that you guys mentioned. But I still had to go again shortly after, and the overall time still wasn't all that long on the can. Like 5 or so minutes each time.
I think my colon's just like that. It may have adapted to all that I used to eat everyday (60g+ fiber, 3600-4200 calories, etc). But I do feel better off now!

I don't push at all anymore.

That may partly explain it. Even with just peeing if we dont push, gravity alone will not completely empty us.
I think we need our diaphragm pushing down on the bladder to squeeze out the rest.
I know its tough keeping the sphincter from opening or closing but very light quick gentle push may work better for you.
I use to also message the area below the stomach while on the toilet to try and help the BM out, which seemed to help empty me.
HTH