Hello,
Sorry you find yourself here, but good place to find out the information/advice you’ve asked for! Sounds like they caught it early which it’s good.
Was diagnosed last year aged 35 with HER2+ I had 8 cycles of chemo (4x EC and 4x docetaxel with phesgo) and cold capped throughout. At first I didn’t find it too bad as I had lots of hair, but I did lose a fair amount of hair and as it thinned I could feel the cold a bit more! I took paracetamol beforehand, some people wear a headband over the forehead where it sits to try to help too. Another lady on my unit used a self heating eye mask for some relief. Generally I only found the first 10-15 minutes to be really cold then you get used to it. This website has information about hair care and scalp cooling:
I didn’t feel unwell during the chemo sessions. The side effects usually started afterwards. My advice would be take your antisickness medications regularly even if you don’t feel sick. Everyone seems to be different in what side effects they get, but always let your team know as they can usually add / change medications to try to help. If you are having docetaxel I’d recommend ‘Suzzipad cold therapy gloves and sock’ which are like cold capping for your hands and feet to prevent nerve damage. It was a consultant at a different hospital that recommended them to me and none of the nurses in my unit had seen them before but I didn’t have any issues with my hands and feet. Also paint your nails a dark colour during your treatments, it’s meant to help prevent nail damage.
As I was having the phesgo (herceptin) alongside chemo I didn’t know what caused which side effect, but now I’m just on the phesgo it seems I get a bit of an altered taste with it but other than that not much. It does sting a bit when going into your leg - I take a little ice pack with me and put it on my leg during the injection which I think helps.
I haven’t changed my diet, I’m sure they’d say to eat a healthy balanced diet - but sometimes between the steroids and chemo etc I just wanted something tasty, cake etc and I wasn’t going to restrict myself 
try to drink lots of water as hydration helps. Things like ice lollies might be helpful in this weather if you’re not feeling like much but want some hydration and flavour.
Sorry that is a load of information thrown at you!! Hope it’s helpful and not overwhelming!!
There is a thread on here with lots of HER2+ ladies you should have a read/join in. I’ll copy the link here hopefully but if not it’s called ‘her2 and need some buddies’:
Good luck!! Hope it goes by quickly for you!