I don't like the Agalhaic Plates from your latest map. It looks like you just separated it because you wanted the plates to push in opposite directions. The thing is, from what I can tell is that the equivalent plate on Earth is being subducted on both sides, because there is force of the main ridge is pushing out on the Continental plates which raises above the Oceanic plate. There is 2 small broken off places from the oceanic plate, but those look like they broke due to stress from the shape of the continental plates rather than how you have your split which seems to be there in the center...

Though I do question if this ridge on both sides is possible like in your map, I think it might slow the spread of the continents by at least half, because you're not just pushing over the plate, but the plate is also pushing back at equal speed... and also 2 ridges like that would indicate that the pressure is being released in 2 places which I think would make the process slow as it is... So if it would move at say 4 cm a year on Earth with 1 ridge, your plates I think would have to be reduced as 2 cm due to the double main ridge and then halved again due to pushing back reducing it to 1cm a year... in other words. If you started with Pangea and was headed to our continental structure, instead of 300 million years, it would take 1.2 billion years to achieve. Though like I said, just a thought.