It's a slight call out, but not one Madoka minds when it's coming from someone so important to her. So even though her smile turns a bit shy, it doesn't disappear. "I'm trying.."

Even though it's hard to be confident. But Madoka at least tries to think of the things she did do this mission, even though the things she didn't do still bother her a little.

But maybe, rather than thinking about that, she should just think about..

"But-- Do you think there is something you'd like to do? To help out people?" In general, she means, not right now. Right now is resting time, that's not changing!