I want to start by telling you how glad I am that you found the words to describe your gender and your sexual orientation. That’s a really tough process, and I’m excited that your work has led you to the identities that you hold.
If you’re planning to tell other people that you’re pansexual and genderfluid, some of them are going to think that you’re just saying it to get attention. They’ll have a lot of pre-conceived ideas of what it means to be young and LGBTQ, and they will make their own judgements. There isn’t anything you can do to change some peoples’ minds.
What you can do, though, is keep being yourself, and keep insisting that people treat you correctly. If you choose to use new pronouns, you can insist that people use the correct pronouns for you. If you date someone of a gender that others don’t expect or approve of, you and your partner deserve to and should be treated well. If people do accuse you of holding your identities just so that you can get attention from others, you can calmly let them know that no, that isn’t what’s happening here, and that you don’t need their validation to hold your own true identities. If they are people you care about and who care about you, they will come to understand you, because they want to be a good friend to you. If they keep insisting that you’re just doing it for attention, then they aren’t very good friends, and you don’t have to remain close with them.
Coming out to your parents can be a little trickier, though. Depending on what kinds of people they are, you might find some success sharing a book or article with them about different kinds of LGBTQ identities first, so when you’re ready to come out you don’t have to explain exactly what it means to be pansexual and genderfluid. You also might prefer to explain it yourself, though, so you can be sure they understand exactly who you are! There’s no one right way to tell your parents. It might take them some time and work to understand who you are. But if they care about you, they’ll put in the work and learn.
You know who you are, and that’s the most important step. You’ve got this.