Rupali - I have a similar dx to you, 11/18 positive nodes, her2+, but ER- and only PR+23%. However, I want to attack it with all the guns I can.
My periods never really stopped during chemo, just got erratic (I was 33 when dx'd). I started on tamoxifen right after my last taxotere (and while on herceptin but couldn't do AIs due to being premenopausal). I had 2 periods when I went into my oncologist for my 3 month checkup after starting tamoxifen. My oncologist said I had to shut down the ovaries immediately, so we started zoladex shots. Essentially, if you are higher risk, like you and I, they'll want to do tamoxifen and ovarian suppression, even if you are low er/pr to be aggressive.
This article will help you understand it more.
http://www.breastcancer.org/r_0511d.html
I'd like to do AIs but my oncologist won't do it unless I have my ovaries out, even though I've been on the shots with no period for over a year. So I guess that's my next step, I just hadn't been ready to do it yet. I've been needing to process the idea of being in permanent, irreversable menopause (which I HATE with the hot flashes) and not being able to have any more children (which I know in my head but my heart struggles with). Although it's either that or these stupid shots for another 10-15 years, and they are not fun.