It's definitely just you. Women go on Instagram to see fashion with links to shopping "the look".
I personally just wear a black shirt and black pants almost every day, am not all that interested in fashion, and am a woman.
No, but it is the third option you ommited: mostly women (doing that).
I just scrolled through Instagram and I think they changed the ads. I still want to shoot myself, but I'm not getting any ads for weapons anymore