Can you get pregnant if..... ?

I been having the birth control implant in my arm for almost two years. and i used to have unprotected sex all the time and nothing ever happen. because I have never gotten a period really since I got the implant. but if I have a small period and then have sex could I get pregnant :/ or am I already possibly pregnant I have read somewhere that shortly after conception you might bleed lightly for a few days. and because it's not normal for me. I wad wondering if this was a possibility.