Is it normal that im not sexually attracted to anyone?

I've never been sexually attracted to anyone without an emotional connection. I thought it was normal and that I'm a late bloomer and that maybe puberty still has that in store for me but it never came. Everyone had celebrety crushes and I dont feel a thing about anyones visual appearance. I learned that my "condition" is something you call demisexual becouse I am sexually attracted to my girlfriend. But my problem is that its killing me when shes sexually attracted to someone that isnt me. It feels like shes not returning all thw devotion I give her and like I cant please her enough for her to be satisfyed with only me. We talked about it and she explained everything about it to me and she reasures me that it means nothing and that she doesnt love me any less becouse she finds someone sexy, but I cant get rid of the pain every time she accidentally (I asked her not to tell me becouse I know she cant do anything to stop thinking that way and she knows that it hurts me) tells me how someone looks hot or sexy. What should I do?