Do I need crutches for a grade 2 ankle sprain? And how should I tell my parents to get me crutches because they think I'm a big baby?

Non weight bearing. If it is painful to put weight on your ankle, then you should avoid doing that as much as possible. The pain is an indication that you are reinjuring the ankle and it will take much longer to heal, and can even result in permanent damage if you continue bearing weight on the ankle. You must have seen a doctor, perhaps that doctor can help convince your parents.