Kind of off topic I think.
I am super quiet. I mumble a lot and girls still love it. I am not quiet and mumbly because of awkwardness it just is how my speech is. I make the girls laugh and if they ask me to repeat I give em shit for it saying they need their ears check (proceed to 'check ear') just have fun and relax. You can be quiet and still succeed.
However don't use your quietness as an excuse to not approach. I may not be loud but I almost always approach and start conversations.
Edit: here are some guys who do this really well
https://youtu.be/mcJiY5rxbyQ?t=22s
Subtitles but even without you can see his quiet attractiveness
https://www.youtube.com/watch?v=hMpqdAYjkhU
Super quiet, but funny and enjoyable.
https://www.youtube.com/watch?v=8v3s3YZuHb8
Another quiet man but he still is a performer and has fun.
Note:
They all are willing to be loud and aren't afraid if the situation arises
They all like to make jokes and have fun
They aren't phased by screaming girls or react to it in really anyway
They would be happy doing their own thing if you are there are not, but they would love to have you along if you accepted their invitation.
They move slowly and smile.
In the Johnny Depp one just watch how he acts when he walks out on stage. That is everything you need to know about the quiet confidence.