So I'm reading the great gatsby and I'm becoming enthralled with the idea that Nick is bisexual or gay.In chapter 4 when Jordan reveals that all...

I certainly can see how one could make the argument.  The
relationship with Jordan does seem to be half- hearted.  This might not be due to sexual
identity, but rather a desire to want to be a part of the social setting of the time.  I
think that once Nick sees Gatsby wooing Daisy, he holds a desire to want to be part of
the same setting.  This might help to explain why he enters into his situation with
Jordan.  I do think that you need to examine how there might be subterranean feelings in
the relationship between Gatsby and Nick.  If you are right in that there could be a
subtext of homosexuality present, there should be some indication of it throughout the
text.  After Gatsby becomes enthralled with Daisy, what is Nick's reaction?  How does he
behave?  Does it seem like he is a friend or confidant to Nick, or something more? 
Assessing this might help address your suppositions.