Must I make up days from last Ramadan because I watched movies containing inappropriate scenes and sometimes did not lower my gaze, and because I am unsure if semen or prostatic fluid was discharged, knowing that semen invalidates the fast?

It is obligatory to lower the gaze from what is forbidden to look at, such as pornography. The discharge mentioned is most likely pre-seminal fluid (madhiy), and its emission does not invalidate the fast. As for the emission of seminal fluid (mani), it is not established by mere doubt; the default is that it has not been emitted until certainty is achieved. As for prostatic fluid (wady), it usually exits after urination.