Hi only had time to have a quick skim. Unfortunately there's not a whole lot you can do if he's falling asleep in the buggy on the way home. Frustrating isn't it! Maybe you could try giving him a snack to eat whilst walking home to try and keep him going?
The days he's doing an A just under 4hrs is when he's napping best. I would make it 4hrs and stick to that for a few days, so put down in his cot at 3.50 giving him 10mins to fall asleep.
Once that nap lengthens you can then fix the afternoon one around it. Also those NW, he seems to be snacking on his feeds you're offering. Have you tried stopping he milk and just giving water?
Is he teething at all? That can really disrupt nights x