There a never ending debate about the ability of a woman to orgasm & what it actually contains.
This is leads to the discussion of squirting.....
IMHO I find it very normal & personally do not think it's all pee; it does contain a certain amount of urine.
Going to the bathroom before sex does help but will not stop it.
I actually use the feeling, push towards it instead of against it, to enhance my orgasm.
Definitely much out there to read about, but it's nothing "bad". Maybe just put a towel down first?