This is often a problem in male-female relationships. Both men and women are capable of being really good communicators or poor communicators. However, women tend to be more verbal than men and have an easier time talking about personal issues, feelings, and relationship issues, leaving guys feeling annoyed, lost or somehow inadequate.
It sounds like you and your girlfriend are at two ends of the communication spectrum. She probably has lots of experience and skills in the communication area and my guess is that you have had fewer opportunities to learn how to communicate about personal feelings and relationship issues. While this doesn’t make your style “bad” or “wrong”, it is clearly problematic for you and probably for both of you.
For your part, it sounds like you might benefit from reading a couple of the many excellent books about communicating with a romantic partner that can be found online and at your local bookstore. You can also attend classes or workshops on communication. You can do this on your own, but it would be especially useful to do this with your partner.
With respect to your girlfriend, it is difficult to know exactly what you are referring to when you say your partner is an over-communicator. It could simply be that she places a high priority on communicating about feelings and relationship issues and this feels overwhelming to you. Or perhaps she does repeat herself and dwells too much on the details of your interactions. Maybe it feels uncomfortable if she is continuously evaluating and wanting to discuss your relationship.
There is no easy way to bridge this gap. By the time we are adults our communication patterns are fairly well set. However, there is always room for personal growth and both you and your girlfriend would benefit from looking honestly at your own communication patterns and trying to meet closer to the middle of the spectrum. If you can become aware of when you are feeling overwhelmed by her communication, the two of you can work out a signal to let her know that you need to limit the discussion or perhaps come back to it at another time. She should be able to honor this request.
Unfortunately, the way to bridge the gap caused by having two such different communication styles is to communicate about them! While this may not seem fair to you, it’s really the only way to find out if you can get on the same page and develop the skills and sensitivities to really make your partnership successful. With love as the foundation and a few good books, classes or a good couple counselor, I am optimistic that the two of you can find the common ground to bridge your different communication styles and have a more compatible and fulfilling relationship.