Can you clarify, Stage 1 meaning that what they initially thought was DCIS turned out to be invasive ductal carcinoma (IDC)?
Given where you are in your life, and your age indicating that your cancer is aggressive, if you can afford it (in the vicinity of $3000), I'd enquire about a genomic test, whether that would be useful. It looks at the specifics of your tumour and gives an indication of how curative chemo can be if you've had some random cells escape that are looking for somewhere else to grow in your body. I'm not sure if it's useful in regards to radiotherapy.
You should also ask your breast surgeon/oncologist about your ki67. This indicates the aggression of yiur cancer as well.
What is your family history? It's not just the expensive BRCA testing that can be done. For about $400 you can do a spit test of up to 61 genetic mutations, several of which are linked to increased rates of breast cancer. It takes a few weeks. Mine went to Sam Francisco. Quicker and cheaper than doing it in Australia.
I think you are right to seek advice about what to ask. You are very young and this is a bugger of a disease that is not fully understood. I'm a big one for asking questions and information gathering. You also have to be your own advocate. With all the best will in the world, we are just one of many patients our doctors have. It is too easy to be fobbed off. You have to become expert in your own condition and be your best advocate.
Get copies of everything, don't hesitate to ask what anything costs and if there's a cheaper alternative. Surround yourself with a team you like and trust, and listen to your gut.
And come here as often as you need! This is a superb hive mind and you're never alone. Big hug, K xox