Could i be pregnant??

My regular 31 days periods became 25days for the past 3 months. And this month i have already missed my period by 4days. For the past few days been having watery to creamy CM. Been experiencing some symptoms but nausea is my normal symptoms before my periods.. so i cannot tell if I’m pregnant or not. There were very light browning colour when i directly wipe my vajayjay but no spotting on my panties. On the 3rd day of missed period i took a guardian pregnancy test and it was negative.

How long do i wait to take the next one?

And can i take on my 2nd pee instead of first if i missed the 1st pee of the day?