FMU - is it really necessary

I remember a while back someone actually advising ladies not to use FMU because they were more likely to get a false negative, but that seems to be against what everyone else says. Does anyone have any thoughts or knowledge they can share? I'm 11dpo, and I'm cramping but they don't feel like my usual cramps at all (and I'm gassy as hell so pretty sure that's what's causing it) id like to test when I get home from work because my mind is racing and driving me mad but is there honestly any point? Would it need to be FMU to show a positive this early? Thanks for any advice/thoughts ☺️