Implantation bleeding?

My husband and I have been trying for almost a year now to have another baby. I struggled with PCOS, but I've been symptom free for almost 3 months and my cycles have returned. I started spotting 5 days early than when I should've started my period, which is always a weekish to 2 weeks late from what the app says. This time it's very light which my period never is, but I do have some mild cramping. I literally just have my period a little over 3 weeks ago. I'm praying this is implantation bleeding and not my period, but don't want to get my hopes up. We do have a 1.5 year old, and I only bled when I was 6-7 weeks along and again at 20ish weeks. I'd love any advice any of you have to give (: