I'm playing in a new group, using Pathfinder for the 1st time. During my third session with them, I was attacked by a monster, and I hadn't used Raise Shield. I was told the attack was a hit, so I wanted to know what the monster's attack roll was, so I could decide if using my reaction for Reactive Shield was worth it. I wanted the option to do an opportunity attack or Shield Block, if the shield's extra AC wouldn't make a difference.
My DM told me that she doesn't have to tell me what the number is. I only then realized that she had never told us the number on any attack so made. She was only telling us if we got hit or critically hit, and by how much damage. I briefly argued that this was unfair, and that it made Reactive Shield nearly useless.
I searched through the rules, but couldn't find anything to back up my argument. The rules do seem to say the DM doesn't have to tell you what they rolled, ever, though.
It seems to me that my DM was technically right, but being cagey about a monster's to-hit bonus is largely unnecessary. So, I ask here, is there a rule that supports either argument? Is Reactive Shield just that much worse with a very secretive DM? Or am I missing something else altogether?