138cm v 135cm

I (F22) just started snowboarding this season. I bought a Salomon Bliss board in 138cm, and it hits right at the top of my nostrils. I am 4'11 110lbs. I can ride it perfectly fine, but all my friends are saying that they think I might be better off with a 135cm... What would that 3cm difference do / how different would it feel? TIA!