What Are Symptoms Of Ovarian Cancer?

I have not started my period for almost 4 months now. Lately, I have been gaining more weight (I eat and exercise good). I have also been having really really bad lower back pains. I have had to stop what I have been doing and they have bee nso bad that I have actually been knocked to the ground and have had my mom help me into the house. I will be sitting down not moving or anything and I have had really bad back pains. I have also been getting dizzy and nausous lately. It sometimes feels like the room is spinning, it doesn’t happen that often maybe two or three times a week.
My question is this a sign of cancer or is this normal?