"I can't really fight."

Or rather - she's learned how to fight in some capacity by now, but she can't fight in any way that actually feels helpful here. After all, shooting an arrow at someone is a little too hurtful to only help with subdueing a threat.

"And it feels like protecting the camp is the most important thing now.."

.. by fighting.

See her problem? It's why Madoka looks so uneasy right now.