If I were you, I would wait until you talk to your doctor before starting the 3rd pack. That would just delay your period for 3 more weeks at least. She could prescribe progesterone or another med to "jump start" your AF.
I know alot of woman on here don't have their AF's return for quite sometime, so don't worry to much.
I also want to mention the chance of asherman's syndrome. Highly unlikely that this will apply to you, but it is scare tissue that can form after a d&c, like I said, only a small, small chance of this occuring, but also something else you might want to ask your doctor about.
Please keep us updated on your situation!
xoxo,
Melissa
Why did your dr start you on BC right away? It's not unusual for it to take 2-3 months to start your period again. Mine took about 7 or 8 weeks to return, and my dr said that was normal. You might double check with your dr to make sure he/she is aware, but don't worry too much. I am sorry for your loss. Take care.