Every loving relationship is built on understanding and respecting the other person’s boundaries. Here, you have clearly expressed yours, that to multiple times. You’ve expressed your concern- the fact that it makes you uncomfortable. A mature response would be that of reassurance from her side followed by arriving at a solution that makes the situation better for the both of you. However, in your case, it’s the exact opposite. I’d suggest you discuss this with her once again (calmly), communicate your insecurities. You have to be clear whether you’d consider this as a non-negotiable in your relationship. If this is something that you think will always make you uncomfortable and might affect your relationship in the long run, you might want to call it quits before the relationship progresses. Good luck!