Is it unfeminist to wear high heels? Only if the high heels are shouting up at you: “Oi, Sarah! Women aren’t good for anything but cooking, cleaning and shagging! Go and make us a cup of tea, will you, love?”
Other than that, there’s nothing bad about high heels, just as there isn’t about most clothes. Complaining about how it’s men who decide what’s sexy in a woman and then promptly stripping off to pose for a men’s magazine won’t help feminism and will make you look silly, but let’s let sleeping dogs lie.