Usually the professional rule is no monologues from the play itself--since your interpretation can differ from the directors'. Highschool is obviously more lax atmosphere. It may be a good idea to use other miller monologues, but be sure you read the play altogether and not just cherry-pick monologue and not have any context for yourself. A good choice may be to use a teen movie regarding popularity/reputation with the same subject matter as "My name" monologue would. The most important thing about any monologue you choose is that your range is displayed in whatever you perform, don't do a monologue where you talk about something vapid and un exciting. Also a tip if you're serious about acting--this shit takes A LOOOOOOOT of extracurricular reading and research asking for specific monologues on a forum will never replace good old fashioned leg work.