Something to consider is current fitness vs goal marathon pace. At your current fitness, based on your recent half marathon, your goal marathon pace is what your current 5k pace converts to. So your mile repeats at goal marathon pace could be too fast and too long, for your marathon goals.
A suggestion would be to train at your current fitness level with longer intervals. So steady state runs at your current marathon pace, tempo runs at your half marathon pace (those could be done in mile intervals as well). And then 800s-1ks around your current 10k pace, and 400s around your current 5k pace.
Might sound a little backward but when you train from where you are, you then can move the needle up in pace as your body adapts. But if you train from where you wish you were, you aren't achieving the physiological effects of each workout's purpose. Basically, train within your current abilities to get faster, as opposed to running faster and wishing your current abilities were different.