I do not know if Herceptin has any impact on return of your period, but mine took a really long time to come back. I was 37 at diagnosis and it returned over 2 years after my last chemo treatment. So don't lose hope yet.
I think that types of chemo you have has something to do woth whether or not menopause is permanent. I read in a book (Can't remember which one cuz I read so many) that cmf causes permanent menopause in 80% of those over 40. That is the chemo i took so I am waiting to see.