Hi NYC
I used to be in recruitment with my last airline. To be frank, its a fine balance between not being over-powering and reaching a "show-off, I'm here, look at me stage" and not being a non-talker as your so nervous.
Its really hard. The whole procress is made up of many different aspects, your application form, your tests, how you present yourself at interview, how you interact in the group and most importantly whether you come across as a follower or a leader!
Most charter airlines are reruiting for temporary junior crew, therefore don't want leader qualities in the candidates. They are looking for people who can take orders and carry them out, whilst looking after the passengers of course and following safety procedures etc.
Don't take it personally with bmi. They interview hundreds of people every month. Very few get through. bmi tend to invite most applicants in and don't spend much time screening candidates, therefore there is a higher number who don't get through. They have a certain "type" they look for if you get what I mean, so do some other major airlines!
Keep going with your applications. You'll find the right airline eventually, and if others don't take you on, well, they weren't right for you anyway!