Go for it and don't get too stressed out... at worst it's fun and at best it's a window into another way for you. Usually Halloween dress-up is a bit accentuated on the fancy/frilly elements of the female look, which isn't really all of what being female is about. Any more than wearing flannel and cutting down trees defines being male. But it's a nice chance to try on some clothes and a persona.
Last time I tried the same for Halloween, I remember four things: (1) the frilly female elements were a pain in the a$$ to set up - fingernail extensions, makeup, clothes, etc. (2) it was fun, and I was a total chick magnet, even at a primarily gay party, (3) I looked pretty good; I could see doing this as a lifestyle if I really wanted to, and (4) I got stalked by a car full of drunk guys in a car on the way home. In the latter case I DK if they knew what was under my dress, but it reminded me that this fear is an everyday thing for cis females. I got away from 'em; that kind of guy is not too smart.
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I swallowed a bug.