I can completely understand your concerns. There haven't documented cases of transferring the virus via breastmilk, but as you stated, it's kind of new and there hasn't been time to do a lot of research.
I think you should do whatever is going to alleviate your fears completely. Obviously, a test will do that. If you are negative, then you can relax. Otherwise, you might just be waiting for symptoms and not know when to stop waiting. But of course it's entirely up to you, and the odds are extremely low that you 1) caught it, and 2) could possibly transmit it via breastmilk.