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.
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