First Time Advice?!?!?!?

Alina
A little bit after my 16th birthday i'm going to be spending a week in a cabin with my boyfriend (and my parents) and im still a virgin, i noticed today how much bigger (girth wise) my boyfriend is than what i use to masturbate and im worried that with my nerves i wont be able to actually have sex. Any advice?? please??? (Note: age of consent where i live is 16)