changing sexuality

so sometimes i’m convinced that i’m gay, but then i fantasize about a random cute guy on the street (never sexually). other times i convince myself i’m mostly straight, and commit myself to finding a boyfriend, but then i never develop feelings for any guy. i would call myself bisexual or pansexual, but i never really like both genders at the same time? it’s kind of like my preference just changes? currently i have a crush on a girl, and that’s the first crush i’ve had in about 2 years, since i broke up with my boyfriend that i wasn’t really into. what do you guys think? does anyone have any ideas as to what my sexuality could be, or experience the same thing? im never attracted to anyone irl but i’m attracted to both guys and girls on tv and in movies. im so confused!!