I always tell F-1 students that if they look at the guidance from 10 different schools, they will get 10 different answers on whether and how a student on OPT and STEM OPT can start their own/can work for their own business. But the law is clear, it's 100% fine while in OPT status and 100% fine in STEM OPT status under certain circumstances. My only advice is that before talking to your international student office, talk to an immigration attorney so that you don't misstep.