"so how many lost tribes are still lost now?"
This isn't even a whole one of the tribes. There are millions of people who have no idea that they are Jewish. I believe the Pashtun of Afghanistan are collectively thought to be a lost tribe.
It's like Pokeman, gotta catch 'em all!
The Pashtun are not Jewish -- they are Indo-European. Pashtuns, Indians, Iranis, Russians, Italians, Germans, English, French etc. are all Aryanic groups -- quite distinct from the SEmitic peoples