Ladies! Could this be my month?

So I had some light brown discharge yesterday and today only on my panty liner and a little when I wiped and now there's nothing, AF is due 12/16. I am 13dpo. The last 2-3 days I've been feeling nauseas first thing when I wake up and in the evening, my boobs are sore and feel quite lumpy, I have a metallic taste in my mouth which doesn't go away no matter what I do, had slight cramps in the lower right side of my pelvis, nothing like usual before AF, also tmi but been getting a sudden urge to open my bowels and it's felt like constipation cramps but then I've had a bm straight away. Also been having heartburn and hiccups when I go to bed and going for a wee loads! Could I test in the morning with fmu or should I wait? Picture is of my light brown discharge I had today