Im too tight to use a tampon 13 help !?

So im 13 i want to use a tampon but im really tight also virgin (ofcourse) in 8 days im going to bahamas so i will swim but im also gonna have my period but i cant get in a tampon in (in here we only have one product and its OB the ones u put in with finger so its hard for me the first time) should i finger myself? ( no we do not have ky jelly too!) so plz help me!!!!