Schizotypal is a real illness. The most comprehensive book available about schizotypal personality disorder was written by Adrian Raine. Reading about or studying the illness might lead to a better understanding of it.
I would discuss this matter with your prescribing doctor. Perhaps you and your doctor could create a plan for coming off the medication, slowly and over time. Part of the agreement could include a directive for resuming the medication, in the event that your symptoms return. It may be helpful to include your girlfriend in your medication plans. She would be an additional observer who might see or notice something that you might find important.
With regard to the problems with your girlfriend, you might be right about her using you but it is important to determine if you are right. A symptom of schizotypal personality disorder is suspiciousness. What evidence do you have to support your assertion? If there is no evidence, then your beliefs are very likely unjustified.
You complained about your girlfriend’s weight gain and wondered what it is about you that made that happen. Don’t assume that you are the cause. Complaints about weight gain are relatively common among couples who have been together for a while. One or both partners may “let themselves go” after becoming comfortable with their mate. She should be made aware of your unhappiness. Couples counseling could assist you and her in addressing this issue.
I want to commend you on your life successes. I wish you continued luck. Please take care.
Dr. Kristina Randle