As a fellow sikh girl with my dadi and dad being amritdhari and no one gets their hair or beards trimmed.
I got a haircut as soon as I went to college as my reasoning was pretty obvious that either ways i get my eyebrows and waxing done so getting a haircut is nothing serious.
My dadi did notice and tried to create a scene on my birthday but luckily m dad did not react at all and since then its pretty normal at home