Well, you are part of a netball team, so talk about netball stuff. Easier said then done, I know.
I can relate because I used to be part of a cricket team and it was all good until I was too old for under16s and I moved into the mens team and I knew absolutely no-one. Everyone was a lot older (about 10-20 yrs older) and it was just a bit intimidating.
I think my advice would be to try and enjoy yourself playing netball. When I play basketball with random people I just talk to them about the game, tactics, make fun of their missed shot and basically stuff like that. Just relax and enjoy playing the game first, and try not be too quiet on the court also.
You said you talk to them individually and I'd recommend that you keep doing this. Hopefully by relaxing more you'll start talking to them more about the game, and also social stuff they do outside netball.
I think you just have to try and break the barrier between you and the rest of the people there gradually.
And I know every I said is easier said then done, but I don't think there is anything someone could say that would be an instant fix. It will be tough making the first move, initiating conversation or joining in a conversation but you need to try and get past that because if you do then you will feel a lot better about yourself afterwards.