IIs it wrong to wear a bikini?

I'm in grade 7 and at my old school everyone was girly and wore bikini's . But now at this school we are having a trip , and we'll be going to the pool. I bought a bikini (halter) and removed the tags. Every girl in my class this year is NOT at all girly and are all wearing full suits. And this girl in grade 7 is going to wear a bikini and they were gossiping about it like it's some crime. And i'm scared to wear it cause they'll think im a slut.... but i bought it , my mom has no problem with me wearing it....should i wear it? is it wrong for a gr 7 to wear a halter bikini?