How long does a normal non combat deployment last?

Sounds like you are deploying in support of Operation Atlantic Resolve. That is a nine month deployment. More than likely, the only way you would redeploy early is for sickness, injury or family emergency. But non of them should be something you should go for. Deployments are great. You get to do your job without all of the garrison bullshit. It took me 14 years to get my first one but then I was on one about every other year until I retired.

Where are you deploying to? Active Duty or Guard/Reserve unit ?

Is it possible that your rotation might not actuslly reach 9 months? Absolutely.