Brown periods

Hey, I havent had a "normal" period since november 2018... First in december i only had brown discharge and no cramps for 3 days and then it was over. I thought my period was coming. In january the same thing happened, ONLY brown no red! In february I woke up to a massive cramps and back pains and i sat on the toilet for an hour just crying because of pain! ( Gross alert) I looked in the toilet when i could finally stand up and it was so red and dark that i couldnt see the bottom. The pain was so much that i laid down on the bathroom floor and couldnt move. After that happened i had red chunky blood for three days and a week later brown discharge came out with alot of thick tissue....

Ladies i am so confused! 3 pregnancy test and all negative, got tested for STD and im clean....Was i pregnant and lost the baby?

Can somebody relate? I think its so weird to just have brown period blood! I was always regular :(