Congrats on getting home with no room for errors with the co2.
I had problems with that I could not get the bead seated correctly and used all my co2's on my first flat but managed to make it on the last one.

One thing I am not clear on is when you say{{
For the third cartridge I mashed the filler head on the presta value and screwed
the cartridge on and got all of the last cartridge into the tire.}}
I screw the filler head on before I put it on the presta valve. I can regulate how much co2 I use as well and not use all of it for a tire. I learned to use little doses so I can be sure the bead seats.

I should have listened to the LBS when they told me to practice before I got one on the road.
I carry two tubes and three co2's now in my under seat bag with multi toll and levers. That is all I can fit in the small bag I have but it works.