1996 Chrysler LHS I need help!

Hi, my name is ron. I have a 1996 chrysler lhs I recently was driving home, went over some bumps(coincedence?) And suddenly the tranny slipped out of gear. I pulled it off to a side street thinkinking the tranny went, put it in park, then back into drive, it engaged. It shifted into 1st, 2nd, and thats it, it will not shift into third or any other gear? It will try but won't? Used a obd II code reader, said the output speed sensor was bad, replaced it. Still will not shift past 2nd gear. Put it back on the obd II no codes, it passes? No check engine light? Has fluid( even though I am not sure what type is in it, I bought it used). I truly have no idea what to think. The only work I have done to it, is replaced the timing belt( if timimg is off can that cause problems? Even though it was replaced weeks before the tranny acted up), water pump, and tempurature sending unit. It does have 200,600 miles on it, seems sound, like it was very well taken care of. Do you have any clue as to what is going on, or is it simply time for a new tranny?