The word since in Russian I believe is expressed exclusively with the words:
1. c = since
2. с (того) момента = from the time
I thing that I listen the following:
"Прошло достаточно много времени как мы общались ..."
The expression in English is: It passed a lot of time since the time we communicated (implied: for a last time).
Is the word kak playing the role of since?
Also I want to write: It has passed a lot of time since the first e-mail I sent you (It is implied that this is the second e-mail):
Прошло достаточно много времени с моего первого сообщения
I pass the meaning I want?