My husband and I are trying to conceive. I am not on anything. My period is due today but have been experincing light bleeding or spotting 4 days before.the spotting is still here but its not like period blood.I have lower back pains and feeling tired and sluggish. Is this implantation bleeding or is it signs of my period. Would it be possible for a pregnancy test to pick up if I am pregnant

It's likely a pregnancy test would pick it up if you were pregnant.
Maybe give it a few more days and see if it is just your period starting and test at that time if need be.

Fingers crossed!