Herceptin For Less Than One Year

I finished 4 cycles of A/C and was to start taxol/herceptin. My muga scan went from 58% to 46% and I could not start the herceptin, only had taxol. Muga will be redone in 5 weeks but onc believes that due to low baseline muga of 58% I will not be able to get the full year of herceptin. I was actually hoping to get 2 years of herceptin as the European study will have been completed by the time I was to finish with the one year.
I'm really scared as there appears to be no other options for me, I'm er-pr- her2+++. Right now I'm stage 1 with no nodes but my mother started out this way and had extensive mets to bones. She didn't have the chemo after diagnosis though and her 1st diagnosis was 15years ago, she died 3years after discovery of mets.
Anyone know what my next step should be, I want the herceptin but don't want to die of heart disease either. Wondering if the A/C did permant heart damage or will the heart recover enough. Major concern that onc doesn't think I'll make the 1 year of herceptin.'
Thanks for your info.