I take issue with this motif in isekais. If a character from that world shows she is open to the possibility of you being from another world, there is no reason not to tell her the full story. In fact, it would endear yourself to her more if you just told her. especially if there has been no established condition that leads one to believe that being revealed as an isekai'd person would be detrimental. "its hard for me to explain..." no, it isn't hard for you to explain. It might be hard for the listener to understand, and it would make for better narrative if that inability was displayed in real time.