Understanding what ER+/PR-/HER2- means for me

Hi all, can anyone help me decipher how “good” or “bad” this is for me? This is a new occurrence in other breast (had pure DCIS just over two years ago). The spot is pretty tiny (2mm) per MRI but Dec 2018 MRI shows it was there. It has grown 1mm in that time and only now took on a suspicious outline. It was never noted to me earlier. Other things I know is that Ki-67 is 10%. I was surprised to hear oncologist mention it would be better it was PR+ too. I didn’t know that, but admittedly have a lot to learn yet since this was a non-issue with my DCIS. Can anyone help me understand why and how serious is it that it’s not also PR+? I’ll note I’ve been on tamoxifen since my SMX. I suppose that is what has kept this so small. Thanks in advance.