I thought she had lost her whole team, but I guess it's a bit more realistic it wasn't all of them. This way it makes more sense she got away alive, rather than managing to escape all alone. But then again, I wonder if that dude was so right with his analysis. If she was thinking like that, then she wouldn't have joined the MC party all. No doubt she has some hesitation, but I think her current personality is explained by two things: She doesn't want to make the same mistake again, so she won't overexert herself nor make the whole team go beyond their abilities thinking the healer can fix everything, and on the other hand she doesn't want to become friends with the new team so that even if some of them die, she won't be as sad as she was when losing her good friends in the original team. It would be more like losing business associates; a regrettable thing, but it happens.
Considering her old personality, it's only a matter of time, though. Not to mention sitting alone at home doing nothing but feeling regret in the darkness isn't all that fun. Every time she gets emotional, whether it's annoyed or just a little bit satisfied, she's losing her detachment.
And yeah, I also think they are normal sized. Must be only the company she's keeping that might make them look smaller, but only relatively.