I don't think shaving your head off every two/three months is helping you in any way to arrest the hair loss. It only gives the illusion that your hair loss has stopped, as the hair no longer gets stuck in the comb as you obviously are not using the comb or you don't notice them fall out in clumps while shampooing. The follicles will continue to get weak and fall off ,only it will get unnoticed.
The Minoxidil 5% you have started using would be the answer to slow down the loss. The only benefit of using Minox on a shaved head is, it might more easily reach the whole scalp without getting wasted . In addition you might want to start with finasteride 1mg.