seriously strange issue with my monthly cycle/period

Okay, so i need help/reassurance from anybody who's had something similar, or have any in take on what the hell could be going on with me right now...cause although I'm usually pretty good at figuring these types of things out..im stumped...so My cycle was suppose to start on July 10th...and I usually am a couple days late, so I wasn't really worried bout it, but I was a good week late. When I finally got it I was relieved. And have come to figure out, that I am not pregnant, so that gets crossed off the list. My cycle finally started I expected to have it for the usual 7 days that I get my period...but it was irregular, not so strange for me. Verry light at the beginning, then about 4 days later it seemed to have stopped, and I thought to myself, oh jesus, I'm pregnant, and the test was wrong, lemme take another, but before the time I even got to take one, it came right back, full on??? But as the days went by, and I had surpassed my normal 7 days cycle...I was wondering...okay..what the heck?? I have had my period for 17 days now??? During this time though..inbetween when i first got it, till now...I would be heavy, and clot...go from there to virtually nothing..I mean, not even when I wiped would there be any pink...kinda like when ur period slows down, and you know it's almost time for it to be gone...I would be free of my pads, and tampons, and wen I least expected it, find a mess down below, and have it full on..again!!! This has been scaring me, and striking me as verry odd. I mean, you can call me the queen of irregular periods, but this has never happened to me before, ever...and I must add, that in March I had an abortion, but since then have had two on the dot regular periods. Nothing strange, until now. Could going through that have given some kinda long term effect? Also my mother has ovarian cancer, this also worrys me, but when I went to the doctor. He never said anything was out of the odinary down there?? If this continues to happen after this week. I am making an appointment for the doctors. Today I woke up, and pulled my tampon, and there was nothing there, a little bit of old brown blood at the verry top. I went about 5-6 hours with nothing to protect leaks, and when I wiped there was nothing like if I didn't have my period. I decided to take a nap, and woke up a mess..and after my shower, I put one in, took another nap, pulled it, and nothing, now awake..with nothing for protection, I still have nothing, but with all this confusion, I'm not sure if it will stay away or come back...with my luck I feel like it will happen to me again if I don't go to sleep tonight with nothin, but we'll see...I need some input please!!! sorry it was so long, and or graphic, but I really really need help. I'm worried, and wonder if anyone has anything to say???