Hello Numbers,
Just a bit of a standard disclaimer before I respond further...

To the best of my knowledge, no one here is a professional. That means that no one is in any kind of position to make a diagnosis as based on whatever symptoms you might present with and even if they were, I wouldn't invest much faith in a diagnosis delivered over the internet. From what I understand, the individuals who participate in this topic are either people who have personal experience with psychosis or perhaps are interested in the matter for some reason -- maybe they're a student, maybe they have a friend or family member with the diagnosis. In my own case, I speak from the position of having undergone the experience known as psychosis in this culture. I wanted to be clear on that because what I say next is based on my own opinion which you can take or leave as you see fit.

I do well academically (I study math), and basically that's the only area of my life where I do well. I'm scared that taking meds will take that away from me, because the reason I'm good is my imagination.

When and if you choose to see a psychiatrist, I suggest you discuss your concerns regarding medication with him/her then. If possible, find out what medications they would recommend in your situation as well as why they would choose those specific medications in your case. Then ask for some time to research them before you commit to a trial of treatment. You are an adult so you do have the right to make your own treatment decisions and as far as I can determine (as based on your posts thus far), you're not presenting as a harm to yourself or others.

Two good resources for researching medication are rxlist.com and askapatient.com. The first link offers a medically oriented perspective while the second is based on consumer reports from individuals who have taken that specific medication. Utilizing both will help provide you with a more thorough perspective. You may want to search the sites by both trade and generic name.

I do have good days, where I can actually function around other people but they seem to be getting further apart. I'm scared of losing complete touch with reality but I don't want to lose the only thing in my life that actually works either.

There are a a number of factors that might affect how well you function around other people, psychosis is only one possiblity. Other conditions that can be mistaken for psychosis include complicated grief, trauma reactions, dissociation, anxiety disorders, etc. For that reason, it might be worth going over your psychologist's concerns in more depth so you have a thorough understanding of why he/she is leaning towards that specific diagnosis. This link might be able to offer you some additional insights into the numerous causes associated with psychosis.

Are you sure the assesment will only be questions, there won't be any scannings or other medical tests?

There are no medical tests (i.e. blood tests, brain scans) that can detect psychosis and/or schizophrenia. Diagnosis is made as based on the observations of your doctors and other reports, such as the history you provide or your psychologist's referral. However, some tests may be ordered to rule out any underlying physiological cause. For example, a brain tumor could cause psychosis (rare, but possible). In such a case, surgery would likely be the preferred course of action as opposed to long-term treatment with anti-psychotic medication.

I hope you're able to get the help that you need Numbers. Whatever information you can gather beforehand will likely be very much to your benefit.

~ Namaste