I was on Avonex for a year following the attack that led to my diagnosis. I had no relaspes while on Avonex, and have not had one in the year and a half since I stopped.
I took a 3 day steriod pulse every four months for 2 years, and now have one every six months. My regiment is different from yours since it's not monthly, but I can tell you that I've haven't had an attack nor experienced a worsening of symptoms since extending the period between pulses.
I had an MRI late last year, and many of my brain legions had cleared, and the one on my spine shriveled like a raisin.
I credit my improving health to dietary changes, supplements, weight lifting and cardio routines, and luck. Make sure to supplement with calcium, vitamin D, and magnesium to protect your bones from the riods. Weightlifting also increases bone density.