If CT scan w&wo contrast came back normal with no brain tumor found 2 years and 7 months ago what's my risk to have one now if I have new symptoms?

It depends. It all depends on what kind of tumor was identified over two yrs ago. New symptoms strongly suggest that you need new studies. You should consult your neurologist or primary care m d. An MRI is more sensitive for soft tissue problems then a ct.
It depends,,, It depends on what kind of symptoms you have and likely if you're worried about a certain kind of tumor. Brain tumors may not have any symptoms, but if they do, anything from a headache to a focal neurological deficit, like a problem with gait (walking), can mean brain tumor. Vision changes can also occur. If you have these or some other symptoms it'd be wise to see your doctor for follow-up.