To make the correct measurement for your feet width, Please follow bellow process:
1.Press the feet on the floor, let the feet endure the body weight. Your feet situation should be same when you wear the shoes and walking.
2.Take the soft ruler to measure the circumference of the widest portion of your feet. (around your feet , see the above measurement picture)
3.Please tell us which Euro size usually wear, we can take that as making reference
Heels weren't created to run in and they're not fit wear. Also, the heels shouldn't be overly slim or else it won't have the ability to support the wearer. If it actually is not possible that you just walk in black platform heels, then do not worry as you could always select the ones that don't have heels.