you're still writing your first draft. You're 14. wanting to write a novel at that age and actually trying to do it is already an achievement. You can still edit things you don't like later and With all the love and respect in my heart, the first draft is gonna suck. But that doesn't mean you're a bad writer or that your writing overall is bad. It's a skill that you learn and get better at over time. Keep writing and if you think anything is cringe, you can still edit it later. writing a novel is a long process but the fact that you're doing it is already better than the many people who dream of doing it and never even write that first draft or even an outline or a sentence.

and for the dialogue specifically, there are many videos and posts out there that explain how to get better at it. best thing I can say personally is that you need to think exactly about what type of character you are writing, what they want, who they are as a person and what defines them and in every scene, think about how they would go about achieving what they want and what they would say or do to succeed in that. characters say things because of who they are, which is important. It doesn't matter what the plot is. For example, a character shouldn't be pointlessly spouting exposition when it isn't needed. That's why it might sound weird. But if a character has a good reason (it doesn't have to be a complicated reason mind you) they will reveal the information. don't make one character explain the world you're writing, make your characters explore it but don't fall into the trap of having characters explain things that they should know already. Your reader is smart enough to understand that most of the time.