How do I stop cringing when I write out conversations?

This is my first post on this subreddit so I hope this is right. I'm writing a fantasy/adventure novel but everytime I draft out conversations, I CRINGE. For example, this is a piece of dialouge I'm working on.

Dragging himself up from his seat, Isaiah sulks his way over to Larissa.

“You know I have places to be, right?” he says, grabbing the two apron strings. He tightens the strings across from one another. 

“Do these places include your house and your bed?” Larissa replies in a humorous tone. 

“Well, no but…”

“But nothing!” She turns her head around, a smirk plastered across her face. “It won’t hurt you to stay and help out for a little.”  

“I know but I need to-” 

“Besides, you don’t have anything important to do right now.” Larissa coughs. 

“Larissa, enough!” 

“Larissa,” Isaiah's expression becomes grim. “I’m...”

“What?

“I have to go home.”

“Home? When?” Larissa’s voice strains.

“I’m leaving.”  

I'm not sure if it's because I haven't been writing for a long time but I can't help to write out a scene in a way I think sounds good and it ends up sounding like a seventh grader writing fanfiction. Is this feeling something I just need to get over or is my writing just amatuerish and in need of improving? Any advice is appreciated!!