3 chest ct scans within a 5 month period (two within the same day). i was 25 at the time. is it highly likely i could develop cancer from those scans?

Just the opposite: It is highly unlikely that a patient develops cancer from just having 3 consecutive chest CT scans. Life in the modern world causes cancer (and of course there was cancer before modern times), but having 3 CT scans will make no noticeable difference when compared to everything else we face in life. In California, we have "useless" signs posted everywhere, warning about cancer-causing substances.