a girl who is into guy x guy and tends to ship a lot of non-gay characters or people
No, in a literal sense it means "rotten woman". As in the characters it is written in in Japanese.
But Fujoshi refers to and you can call females who like BL (Boys love) or Yaoi (more intense eg. further than kissing) that, and they may ship male characters together because they like BL.
The opposite of it is fudanshi, which refers to males who like the same thing.
I proudly declare myself one of those. It's not derogatory, the term literally means that. It is a term used widely by many fans today.
It's a term used for calling female fans of Boys Love and Yaoi. As the characters originate in the Japanese language, the characters it is written in happen to mean that in a literal sense.
https://en.wikipedia.org/wiki/Yaoi_fandom
It just means females who like Boys Love and/or Yaoi. ლ(´ڡ`ლ)
Which, to answer that, is that your guess is not on track.
I'm not very good at explaining. Sorry if I'm not able to answer your question properly.
Fujoshi and Fudanshi translate as "Rotten woman/ rotten boy" - it's not someone being judgmental and calling others names, it's just the actual meaning of the word. A fujoshi is a woman who likes to read about homosexuality between men, the term does not refer to a woman who is interested in straight guys or wants to have a relationship with straight guys (that's just a normal woman...).
What is the meaning of fujoshi ?