Well, cookie, I was wrong.
My guess was June 1993, if you recall.
However, I looked your transit chart again, and surprisingly found transiting Pluto passed your 19Sco32 ASC three times from Dec 1990 to Oct 1991.
It surprised me because I did not think your personality change could link so closely in time to substaintial incident in reality.
I thought that transit should not be so obviously noticed...
On the other hand, from the progression point of view, there was nothing drawing my attention, except solar arc Mars approaching your natal MC which should stand for your mother at that time.
Ironically, during that time, solar arc ASC was approaching your natal Venus in 1st House, that means you were conciously becoming more beautiful, or handsome if you are male, or just felt being loved.
Kai