Can somebody help :)

Shannon💗 • Ttc #1 so in love 💕
Hi guys, I'm 19 and currently trying for a baby! Iv got a full time job, my own house and a fiancé ? 
Iv been on previous contraceptions 
>the pill 
Iv been off the implant for nearly two years, off the injection for a year and stopped taking the pill in August, which I was only taking for 2 months. 
Iv been trying since iv came off the pill, and nothing's happened, my periods have been at the same time every month since. On Monday I went to the toilet at work and notices a brown splodge in my knickers; then about 2/3 hours later I wiped and there was the most small amount of blood ever on the tissue ... Inplantation ?! But I researched and it said my implantation would happen on 24th which is tomorrow. 
Symptoms; iv been feeling sick(not actually being sick) massive headaches, getting out of breath easily, feeling more tired than usual, and feeling mega hungry all the time. 
It says my period is due in a week (7 days) I tested tonight, I should of known it would of come back negative but just had a little bit of hope. 
Do you think that I could be pregnant?! Or not ah! Thoughts are welcome, and answeres would be lovely :)