I had the same type as you. So I had surgery, chemo, Herceptin and radiotherapy. The treatments started in June 2016 (diagnosed in May) and my final Herceptin was August 2017 so it is a long hard slog but I am still here!
I used a cold cap and kept lots of hair, I fasted before chemo and my symptoms were minimised. The medication made me gain weight and made me develop aches and pains in my joints. You can get relief from that if you take a couple of claritin hay fever tablets one morning and one evening here's why:
Please ask if you want to know anything xxx
I didn't have the same type of cancer as you but there are many ladies here who have and regardless of type, stage,size etc the one thing we all have in common is the fear of recurrence and spread so we all understand how frightening this is for you. The best advice is not to google, almost impossible I know but it just feeds your anxiety, there will be success stories out there they are just not as widely published and our brains will always latch on to the negative we read!
We have ladies here many years on from a HER2+ diagnosis and still doing fine and I personally know one who is heading in to her 4th year cancer free, yes it tends to be more aggresive but they treat it accordingly.
You have had a great response with shrinkage from your first Chemo so see that as a huge positive and a sign that your cancer is being knocked on the head! That is the bonus of having Chemo first so you know from the off that it's working.
It all gets a little easier as you plough on, just try not to think too far ahead and just deal with what's in front of you now, speculation will get your nowhere and it just drags you down as you fill in the missing bits and you end up writing yourself off.