Re: Should I tell her that it's time to call it quits?
I can understand how you feel. Relationships require a lot of open communication and when she isn't expressing her feelings it can make you feel that way you describe.
It's possible its just her personality that she isn't open. It may not even have anything to do with you as a person, just the way she is. She may feel too uncomfortable to express how she feels. It can be a number of reasons. But obviously shes the only one that knows what she feels but if she isn't open you really can't find out and you're left in the dark.
I'd say give it another shot in trying to get her to open up otherwise it may be time to call it quits and explain why you are doing so.
In relationships you have to be open on both ends for it to work and not getting that is just too difficult and can make you feel miserable. Don't put yourself through that. Give it another shot otherwise best to call it quits.