Wear what you want! At 59 years old, I got curious about bras. I tried on my wife's bra (38DDD). The hug from the band was amazing! Within a few weeks, I worked up the courage to ask for a fitting. I'm very happy I did.
I asked myself the same question after I had been wearing only panties for a few years (I started wearing them when I was six). Since then I have become a real "clothes horse", having more (female) clothes than my wife! So, to answer the original question, I will ask my (revised) version of the question, which is: Not 'what if', but when will I end up wanting more than just to wear panties?
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Put me in a bra and panties, then watch me turn into a very naughty girl. I don't know how or why that happens, I just know it happens and I love every minute of it. After all, it's true that naughty girls do have more fun.
Same here: Started out with just panties, because that was easier to hide. As more people become accepting of it, I found myself experimenting more into other lingerie and dress. I've found myself purchasing what I want to wear, and what I think looks cute with my existing attire.
I may wear button up shirt, and slacks at work, but I can guarantee that underneath I have on a garter belt, thigh high stockings, a bralette and of course panties over the garter straps (Because that's the right way). And no one beyond my wife is the wiser about what I have on.
It happens... while I bought a bra I only wore it a couple of times and just didn't care for it. My fetish runs toward the texture so a silky cami, panties or hose that feels sexy on my skin is amazing.
Shoes and skirts and makeup have no interest in my world.
Feeling feminine??? I just don't.
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Everything she wears is magic, everything she does just turns me on.
I also have had really no interest in things other than panties. I'd probably wear a skirt, but that's just because they seem pretty comfortable and nice to wear on a hot day!