Firstly there are a couple of horribly discouraging comments in here, some people need to realise that not everyone here is playing top level cricket or on top level pitches!
Also I don't think it's true that you have to be the team cheer leader, you can be a top keeper and still be a quiet person. Somebody else who fields in the infield can do the shouting if that just isn't your thing.
The nature of the role does make it difficult to get a chance at times. I spent a long time at my club when younger pondering over whether to play 2nd team cricket and keep or to just bat in the 1's where the keeper was pretty much entrenched. In the end the other guy quit the sport fairly young so the slot opened up and have not looked back since. I do wish I had got the opportunity earlier though as didn't become a regular keep until I was about 18 or so.
Are there Sunday games/midweek fixtures you could keep in? Maybe in indoor team? If not then would you consider dropping down a team to give it a go? If these things aren't possible and you really want to become a keeper then you have two choices; wait or find somewhere else to play.
Good luck with it, it's another fantastic opportunity to buy even more lovely kit if nothing else