Scared to have sex...ugh help?

Tais

Okay so I am so definitely really to have sex and so is my boyfriend. (I am a virgin, he isn’t) The point is, that I’m scared that when we do his dick won’t fit! Like I’m just scared that when we want to have sex it won’t happen. We have like little to no alone alone time so I hate for that alone time to not even work!!! Is there any way I can make sure that DOES NOT happen??