What Causes Difficulty During Urination?

More recently I ve noticed that I have trouble urinating. I ve noticed it happens when I take my adderrall. I drink lots of water, around a gallon a day and when I have to to it feels like my bladder is full. When I go to bathroom, it takes a while to start, stream is weak, and it feels like I don t fully empty my bladder. I ve been on adderral for a year and this is maybe been going on for a month or two. I m 27 years old and male. I have an appointment with my physician in two weeks and was wondering If I should bring up the question of my prostate.