Think i found lump in my ....24yrs old...what to do? Scared?

so, back in like feb i felt something in my right ...i immediately went to both of my doctors who told me that it was nothing and that i naturally have lumpy . so, i was relieved, but i'm pretty much a hypochondriac and i give myself weekly breast exams even though it only needs to be once a month. anyway, in my left breast now i feel something, but i'm not sure if its suppose to be there or of its a rib. now, i'm really scared. i mean none of the immediate women in my fam have had breast cancer...no aunt, mom, or my grandmother. they said that my grandmothers grandmother had breast cancer, but that's so far down the line. i of course called my doc to schedule a physical and get everything checked out, but they said she can't get me in until July 18th!! i'm so paranoid and cannot wait that long. do u all have any suggestions...i'm not sure what to do. is it even common for women in their 20s to get breast cancer?