Could My Recent Lighter, Shorter Period Be Implantation Bleeding When I Have PCOS And Irregular Periods After Years Without Menstruation?

I have a question? I am 29 yrs old i finally got my period for the first time in 3 years i have PCOS i got my period back in march of this year then didnt get another till june then another one in aug i had one last month that lasted 7 days and it was heavy with really bad cramping i started on the 3rd of this month and it just lasted for 4 days and it wasnt heavy nor did i have cramps i lived in arizona for 3 yrs and the doctor there said i had thyroid problmes then i moved to indiand and seen the doctor there just last year and she said i didnt have it anymore my test where good i just dont know if my body is trying to tell me something or it was impation bleeding