Well, I recently began dating a woman whom I find very attractive. She is very petite and in good health. We have tried to use lubrication, and I have tried to pay attention to her cues and be responsible for my own pleasure, but frankly I'm not enjoying sex very much, and I don't think she is either. This has not been an issue with other partners in the past for either of us. You're on the right track.
Communication is one of the most important aspects of sexuality between two people.
It is possible though, for a penis to be so large that it can cause discomfort to both partners, particularly if the woman is very small inside. While this combination is unusual, there are various positions that can be helpful, especially when combined with lubricant. These positions can allow the woman to have more control or to decrease the amount of full penile penetration, which can help lessen or prevent the internal discomfort your girlfriend is concerned about. Enhanced communication and longer, mutually satisfying foreplay is also helpful. You did not mention how long you have been dating this person, but being with a new partner brings about nervousness for most people.