No. nerd glasses now are the most fashionable glasses and widely spread among young generations. Wearing proper pair of black nerd glasses can make you look in a smart way. My younger sister have bought a pair of thick black nerd glasses with big frame two months ago. The nerd glasses compliment her very well. So, it won't be weird for girl to wear black nerd glasses. If you like it, don't hesitate to wear it.
That depends. Some people look very cool and attractive with black nerd glasses on. While some people look weird with the big nerd glasses on. Therefore make sure the big nerd glasses can suit you best before you go to get your prescription big nerd glasses. The best way is trying them on to see whether they are suitable for you. Or you can try them on online because many online optical stores have try-on system. As long as they look good on you, you can get prescription big nerd eyeglasses.