Do you think it could be ovarian cancer?

I have had constant bloating, abdominal pain, change in bowels, frequent urination, and random hardness in my abdomen. This has been going on for several months now. I went to the doctor when it all began and they found nothing, but it continues to effect me every day and I know there must be something wrong. What's happening with my body is not normal and I don't believe the doctors were correct that there was nothing wrong with me. I have researched my symptoms and everything points to ovarian cancer. I'm only 21 and am very scared that if it is ovarian cancer I wont be able to have any more children. What do you think it could be and/or do you think it is ovarian cancer? Please help!?