That was very nice of your co-worker, you'll get it! I can empathize, there are times, when I go to ask a quesiton, I"m so nervous, I'll stutter, it's.....Lord take me now;-)
If someone comments on you being quiet....So what;-) I can think of worse things than being quiet.......
What you're doing takes time and practice, before you know it, you'll be thining "I'm bord" what's next.
How did you find this job? Interviews are my nightmare.