Pregnancy or is my body palying tricks on me?

Ok I have a normal 31 day cycle it comes on like clock work it lasts four days max when it does come on. Ok my last normal period was Jan. 16th so I was due for it on Feb. 16th but it came on a day earlier which was Feb. 15th nd it was not normal I spotted pinkish/clearish mucous all day that day...the next day the flow was a lil heavier but not the normal...it was pinkish/brownish spottin and it went away!! I haven't seen anything since...except all these pregnancy symptoms...nausea vomiting headaches frequent urination extra tiredness and I've been emotional nd moody...I had a pregnancy test nd u/s done at the hospital but it came up bfn....was it too ealry to tell? Could it have been wrong? I'm due for af on mar. 17th so I'm tryna hold out on another test till closer to af due date!! Its crazy but I really feel pregnant I'm not my normal self these days...could dat last supposed to be period have been implantation bleeding? Someone help please any answers could nd would be helpful!!