Great Job!!
I pretty much did all that you said... the gate are the answer.. I used cheap extendable window screens,, for hallways. It seemed if he had the option to get out of my sight,, he used it!!
I think it was about a good 6 months until, " I " got potty trained,, thats really what it is... he never really had any signs to show me it was TIME.. and he would go to the back door, where I wouldnt see him,,when it was time, then at about 6 months , he would go and sit on the side of the TV and stare at me,, and make a faint whine,, and I'd say " Oh, it time"
he is 9months now,, and we are doing well,,, cant remember the last time he peed in house,, but occasionally we have a poop accident,, which I still havent figured oout??
but that is very few and far between! Sounds like you are doing fine!