How do I clearly bring up pegging to my girlfriend when she said she doesn’t like butt stuff?

I am a [20M, 6’2”]and I want to talk to my girlfriend who is [21F and 5’1] about pegging me. The first time I mentioned it she thought I meant doing anal to her. She told me she doesn’t like butt stuff, but I honestly don’t know if she meant only for herself or if she meant anything involving that area in general. I didn’t want to make it awkward so I let the conversation die, but I’m still curious and I want to communicate better.

I also don’t want her to see me as less of a man for being interested in it. I know some people have certain ideas about masculinity and butt stuff, and I don’t want it to change how she views me. I just want to ask in a clear and respectful way while making sure she knows I meant me receiving, not her.

With our height difference I’m not even sure how the logistics or positions would work if she was open to it. If anyone has experience with that I’d appreciate any advice.

How can I bring this up again without making it awkward or making her feel like I’m ignoring her boundaries? And does height difference actually matter for this?