TTC after Mirena

Removed Mirena IUD on 8/12/15 after 2.5 years with no AF. Removed IUD with no spotting or bleeding. 5 days later spotted for 2 days (wipe only). Yesterday started spotting heavier needing a liner with small period like clots and slight cramping, but no where near period level. Doctor said to wait until after first AF to TTC to make sure lining is thick enough. I feel like this might be AF because the lining isn't thick enough to have a full AF. But I have no clue when I can expect it. Any experience with AF after Mirena you can share? Could this still be removal spotting or just a light AF??? Please help!!