You can and probably should get a second opinion, but most good doctors won't order more chemo based on CA-125 levels alone (which could be influenced by many factors). And there have been new studies released that show that restarting chemo earlier than necessary based on CA-125 levels does not affect outcomes, and may in some cases, cause more harm.
It sounds like your doctor is up on the new methods, but get a second opinion just to ease your mind.
I would be worried. What stage were you originally diagnosed at? and what type of pathology did you have? If you are unable to get the direct answers you deserve from your doctor, maybe you should get your complete pathology reports and operative notes and find yourself another gyn/oncolgist.