Swim with a black swimsuit with no coverage?

ok so im on my period... i wear pads.... not tampons! tampons are WAY out of the question because im only 11 and my mom doesnt even use them! and im going to a boy/girl swim party on thursday and i dont want to mis sit! should i say i have swimmer ear?!?! ORRR i have a black bikini. no polka dots or anything just plain black. my flow is barely any if im not wearing a pad it only stains my underwear in a few tiny spots here and there. so can i wear my black bathing suit with no coverage?! or should i just use a little bit of toilet paper just in case!? remember its a boy/girl aprty so i cant a trail of blood following me around even though i dont think that would happen!! PLEASE HELP thank youuu(: