I've never been with a squirter. Not sure I'd want to. I read above that it's a mistake to think it's pee (though if a girl mistakenly thinks that squirters squirt pee, and she wants to be a squirter too...)
The thing is, I once tried to research the gland or structure that secretes vaginal lube, thinking it would be analogous to a salivary gland or a tear duct. I discovered that there is no such gland, no female analog of the male Cowper's Gland and prostate [edit] within the vagina [/edit]. Vaginal lube is simply intercellular fluid like you have throughout your body, which the vagina walls excrete in response to stimulation. The only significant muscles in the area are the PC muscle that squeezes the opening, and the uterus. I've read that during orgasm, usually, the cervix opens and the uterus expands to create suction, actions which help facilitate fertilization. Squirting seems to act against this, which makes it something that would impair fertilization... which makes squirting something that evolution would have bred out of mammalian species long before the existence of humans - unless squirting was an evolutionary response to prevent pregnancy after having been inseminated by an unsatisfactory mate.
But, as I said, I've never been with a squirter. And, since I don't have a vagina, I can't speak from personal experience, only from what I've read. Even though having a penis does not impair my ability to read, there are some who would disparage my remarks as "mansplaining". So, I'm NOT SAYING that squirt is just pee, I'm NOT SAYING that women can't squirt something other than pee - I'm ONLY reporting what I've read on the subject, and saying that despite my research, I can find nothing that could make it possible.
But, if people are happy with the things that happen when they are together, then it doesn't really matter exactly what happened or how it happened or what anyone else thinks of it... carry on!