Implantation bleeding Vs period bleeding

Hi all! May I ask , how did you notice it was implantation bleeding and not your period spotting? 4 days back , I notice light streaks of blood in my undies and when I changed & put some panty liners on , there wasn't any blood. It went on for about 3 days (the light streaks). I'm anxious as what other reasons can we bleed from below right? If this is really implantation bleeding, when would be best to test for pregnancy? I'm unsure with this process as with my toddler back then , I totally didn't realise I was pregnant until I was 6 months into the pregnancy. So it was back then a shock as we were not prepared. right now , I'd want to prepare myself better if I'm really pregnant with number 2. I humbly seek your expertise / advises and would like to hear from those who have experienced this. Thank you!! #worryingmom #advicepls #pregnancy