Working of SSRI medication for OCD.

Sir, I was taking Fluxotine 20mg for last 7 years. Right now I am taking Fluxotine 30 MG due to increase in ego-dystonic thought. I was learning about how SSRI medication works. It will inhibit the Reuptake of Seretonin by the pre-synaptic cleft by blocking the receptor which is responsible for re-absorption of Seretonin. So, in turn level of Seretonin will be increased in the Synaps. But my question is , how that will help in preventing obsessive thought and compulsion ? I was reading a hypothesis that thalamas sends the report to pre-frontal cortex when a task is completed. But in case of OCD patient thalamas is unable to send the completion report to cortex, which in turn cause repititive action. So, my assumption is that path will be free with the increased level of Seretonin. So that Thalamas sends correct report to Pre frontal cortex. Is my understanding correct ? Or SSRI works in a different way to prevent the obsession and compulsion. Please clarify in medical terms.