Guy cross dresses to get close to a girl

Ok, so I am looking for 1 particular movie for a while now. I saw it when I was younger and I do not remember the name of it.
The plot involves around a guy who meets a chick and immediately falls in love with her, or something among those lines.
The girl in all girl collage? high school? not sure... So the guy decides to cross-dress as a girl and enter her school in order to get close to her.
And like every other romance, the guy gets the girl in the end.
This is supposed to be a teen comedy - romance kind of movie.
Now I am not sure about this, but there might be a part 2 of the movie, continuing their relationship... except he finds out that he haves uncurbable disease and decides to end relationship with her, which also ends up with her finding out about it.
I am not really sure if there was 2nd part of the movie, or my mind is just playing tricks on me.
But if anyone knows this movie, let me know about it!

Thanks!

Two that come to mind are Nobody's Perfect (1990) and Little Sister (1992)...

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When you say, "old" can you narrow it down to a decade range when you watched it? Are we talking 2000s, 1980s or even an older black and white flick?

I've changed the thread title to be more descriptive, per the warning beneath the title field:

There was a TV series Bosom Buddies. Two guys dress as women to get a cheap apartment. One likes a nurse. He pretends to be sick to get sympathy from her.



https://www.imdb.com/title/tt0080202/

There's a movie from the early 2000s called Sorority Boys. Just throwing it out there. I haven't seen it (and the motivation for the cross-dressing seems to be not motivated by a crush).