I can see the upside to that. When you have the op first and chemo later, the surgery part hasn't completely healed and the chemo does mess with it a bit. I am having lymphedema and cording in my arm and my oncology said its the chemo fiddling with it so you having chemo first to halt that rampaging cancer straight up is a good thing. It might also grab any stray cells floating around weeks earlier too, right when they aren't assembled ready to do something nasty.
Hormone positive is also a good thing believe it or not as you can take tabs for years which will stop the cancer cells bonding and starve them of the proteins they need to grow. Not so great as you get menopausal troubles but hey we are all going to get those in life anyways.
You will need someone to get you to all the appointments, and do major shopping so if you don't have family or neighbours, ask the cancer council and they will figure something out.
One good thing about you doing a lot of sleeping in chemo recovering, just think how much quiet homework the grade 12 will get done! Its early in the year so hopefully you will be back into things by graduation. That's a very nice goal to look forward to.