Advice on spotting? Pregnant or implant/rod

I had my contraceptive implant/rod out on the 15th of February so just over 2 weeks me and my partner are trying so have sex regularly since. Over the last few days I have been bleeding a little then it stops then again the next day my period isn't due for 4 more days and when I've tested its been negative 

Is this possbly implantation bleeding or is this due to the implant removal? Is it possible to catch that fast? Anyone had any experience with this please I dont want to get my hopes up but its hard