TTC first time trying

My fiancé and I conceived the first of this month. I haven't really felt any symptoms besides nausea but never thrown up yet. My period is pretty regular and "should" start on the 19th of the each month. Yesterday I had some brown spotting discharge for a few hours and then it stopped, I thought it was implantation spotting/bleeding and I wake up today and I was bleeding..it was a bit on the heavy side. I'm just not sure if that's part of the implantation bleeding or if that's me starting my period I can't exactly tell. I took a pregnancy test on the 15th of this month so 3 days ago and it came out negative. I'm not sure if I took it too early but I would just like someone's opinion on if I'm experiencing implantation bleeding or if I'm starting my period the next day I got severe heavy bleeding, I'm not sure if that's my period or something else. I'm trying to get pregnant and this would be my first time trying so I don't exactly know what to expect and I would like someone's opinion.