I think having things sound like a wattpad fic is a part of the evolution of your writing, so I wouldn’t shy away from it. That being said, two of the things I can suggest is this:
1) if you’re unsure it something sounds real and genuine or cringe, then read it out loud, even if it’s just to yourself. Hearing it spoken aloud makes a huge different for dialogue especially.
2) Don’t shy away from learning! There’s a lot of criticism on Twitter when people try to explain grammar rules to others but I’m of the mindset that if you personally want to get better then all of that is great advice. Finding your own voice in writing takes time but I think it’s super important—it makes whatever you write so uniquely you and that’s what people are drawn to.

Other things: outline your fics (especially if they’re long/multi-chapter) and if super in doubt then ask around for a beta reader! Myself and sooo many other writers on matz Twitter are always eager to help (though it takes me a bit longer to get through DM’s, sorry!)

Most importantly though, don’t get discouraged! I have fics on my AO3 that I wrote 15 years ago and sometimes looking at them makes me genuinely cringe 😅 but like I said, it’s part of the evolution of writing and ultimately one day you’ll look back at it and realise how much you’ve developed! Hope that helps!