Wow, I've been doing exactly the same thing lately...and I also dress down most of the time. I have since I was 20 and I'm nearly 40 now.
For the same reason as Echo (I think it was?) said...fear of my own power, fear of attracting the wrong kind of attention...and getting so used to moving under the radar and liking being invisible. I've noticed in the last couple of years that I really want to be seen though. I want to stand out...and I've been off relationships for so long, but I'm sick of that as well. I'm sick of my own company. I've had enough of being alone and whilst my cat gives me lots of cuddles and affection, it's just not the same.
I have trouble feeling comfortable with standing out though...and have for as long as I can remember. I hate drawing attention to myself, but I also want to attract the right people. Today, at work I dressed up and wore make up and one of the women I work with noticed and said she didn't recognise me, which felt nice.
I was happy at one stage dressing down, and not for self-esteem reasons...just because I wanted to feel comfortable and not have to attract anyone. I believe in what someone else was saying earlier, that attraction can occur on an energetic level mostly...and it doesn't matter as much what the person looks like. Cultivating inner beauty is definitely time well spent, but I also know I feel better when I do 'make the effort' despite being anti make up for years, and on the whole natural kick. I prefer not having to wear the mask, and I think that is what I've been doing lately as I'm going through a lot inside and having trouble with it. The mask can help me feel like no one will notice.
I also don't smile in public, and haven't for 20 years...as I just started getting weird guys thinking if I smiled at them it meant I wanted to f*ck them, or I was their girlfriend. If they didn't take things the wrong way it would be ok, but there's so many distorted perceptions out there, and the male friends I have...well, there's really only one guy I'm kinda into, but even he kinda repels me at times.
I was listening to a very interesting woman the other day on a podcast...her name is Zeena Lavey, and she was speaking about how dressing up to attract can bring a woman a lot of power in the sense that you get a lot of attention and the men will share lot of information, and knowledge, which is power. I'm aware of that, I just have trouble feeling comfortable with that power. It feels safer to move under the radar. I get male friends pitying me though, or saying "you're plain but you could be gorgeous if you wore some make up." Nice eh? I think I look all right just without make up, but it obviously highlights your features and can look good at times too.
I don't know? I'm in the same kind of pickle. I just want to be me and not worry about any of it.