I do think you are right about the need to increase A time and move towards a longer EASY. You're approach seems good too - just adding a few minutes at first. You're also getting good results by using a shorter A time after he first broken nap so I'd definitely say follow your instincts.
The only "issue" to note, although I hesitate to call it that, is the napping in a baby carrier rather than in a cot. I say this because the "ideal" EASY is aiming for independent sleep. There is a risk that your lo could become dependent on being I the carrier to nap. However, he Is still really small and hey grow big so quickly, it is not a negative to enjoy this time with closeness. Also with an older LO it can be harder to find time to sleep train at this stage, with so many naps. So really what I'm saying is this is on,y an issue if you begin to feel it is, and you can deal with it then.
Hope that helps
N xx