Body going crazy. Need advice

Okay I've been on METformin for about 2 years.. my periods came back.. we've been TTC but this is our last month we were planning on trying due to some other medical problems that have come to light, that I need to get under control. Anyway my last period was august 25th then came the light bleeding on September 8th apparently according to this app I ovulated the day after my period stopped. That would make me 11 DPO right now. Is this implantation bleeding? Should I wait on taking the new meds I was prescribed until I get an actual period? (They are harmful to pregnancy) I'm so confused on what's happening! Any advice?