Am I (23M) being silly about my relationship with (23f) fiance?

Hello. So I (23M) am having trouble with my fiancé (23F). We have been together for 5 years and engaged 2, and she is amazing. She supports me, is funny, caring, loving, etc. yet I can't shake this feeling that it may not be right and I'm not sure why. We are in the midst of planning a wedding and I am reluctant, but I'm not sure if I'm being silly or not. This is my first relationship so I have zero previous experience, and I feel nothing but pressure from my family as if they don't like her. When she gets upset or anxious (which is often she's an anxious person) I get annoyed now instead of being caring. I can't tell if she's good for me or not, I need serious help and am not sure if I'm making a mistake.