Sorry about your mom.
A lot of what you are experiencing is growing up.
Your body is developing.
Many young women gain a few pounds once their menstrual cycle starts.
The pelvic pain can be cramps, or you could have some ovarian cysts.
Every woman--young and old--tends to have some bloating before and during her menstrual cycle.
Your uterus and ovaries are covered in layers of skin and muscle, so it's not easy for you to see them just by looking at your abdomen.
But, since you are worried about yourself and since there is a history of ovarian cancer in your family, I'd suggest to put your mind at ease, ask your Dad or Aunt or even your Grandma to make an appointment with your doctor.