My are kinda hard?

I'm 14 and just started my period not too long ago. idk if that has anything to do with this but my are kinda hard. is it normal that about a centimeter thick past the squishiness, it's like a hard mound? I'm not talking about little lumps everywhere... just like a giant one under the skin. it doesn't hurt or anything. just if I press down a little, it feel like there is like a... a tenis ball kinda feel perfectly centered underneath my nipple. is there something wrong with me? also, how early can one get cancer?