Is there a way to reach higher notes when singing without being too loud? i'm a guy?

alright, i'm a tenor in chorus, but i was just moved there from the baritone section like a week ago. my voice teacher says i have a high range, but some of my friends say i can't sing up high, but most of the time when i'm singing in front of them it doesn't sound all that great because i don't really sound good on high notes unless i sing loudly. is that normal for everyone? and is there a way i can sound better on my higher notes without being obnoxiously loud? my range usually varies from day to day, but most of the time my lowest note is usually an E4 (lowest string on a normal guitar) or an F4 (a half-step up from that), and my highest note is usually around A6 (2 octaves and 2 1/2 steps from E4). i'd ask my voice teacher, but i only have lessons once every two weeks, and i don't have one this week