My 18 y/o is going through similar stuff at her job this summer. She now knows God has put her there for a reason and has started subtly witnessing to her co-workers. Now after a few weeks they are talking to her about God, how she stays faithful to Him & how they think they are not good enough for God & church.
Keep praying for your DD that God will use her to reach her co-workers, of course she shouldn't "shove it down their throats". Remember God has a plan for her in this job!