Being overweight wouldn't matter, no.
Being obese or morbidly obese would naturally push your bladder down and there is a surgery to have your bladder lifted. My sister had the surgery done and it helped her immensely.
Having a child sit on your bladder for nine months doesn't help either lol but comes with the territory.
The problem that I've noticed in my research is that the act of squirting is extremely hard to study. There are several theories about it, but most of the time I've noticed that no one really teaches it so a lot of women think that it's abnormal. If it happened or if it doesn't happen I still think it's all natural.
I think that's why they make waterproof mattress pads lol.
Best of luck!