implantation or period

iv been having all the signs of me possibly being pregnant but not getting myself too excited, i have period apps, which told me when i ovulated, i think i may have ovulated later than expected as im due to get my period in 3 or 4 days and iv had some bleeding, could this be implantation bleeding?? iv been feeling really tired to the point sleeping for hours, nausa every afternoon, not hungry, then craving chocolate like mad, boobs hurt , back hurts , cramping and the list goes on , sorry for the long post, what do you think??