[Grammar] It has been a while

[ha179]

I would like to say I haven't seen someone for a while. Which one of the followings is most appropriate? Thanks a lot.

1. It has been a while since our last meet.
2. It has been a while that we haven't seen each other.
3. It has been a while since we've seen other.

Although I've read this thread and its answer, I'm still a bit confused about it. I would also give the same answer as engee30, since I was taught about the structure It has been (a period of time) since S + last + V-ed. But I'm wondering if the first two of the three options originally given by spaceniuzai are acceptable/correct, too (I suppose the third is incorrect).
Really sorry for creating this thread just to ask about the issue already asked and answered, but I just want to know if there are alternatives to express the same idea in this case. Thank you all in advance!

 

[BobK]

...I was taught about the structure It has been (a period of time) that S + last + V-ed...

What were you taught about it? The only thing I'd teach about it is 'IT IS WRONG'.

b

 

[ha179]

Really sorry for the unintentional mistake. Actually "It has been (a period of time) since S + last + V-ed" was what I was taught, as far as I remember. I will edit my post. Thank you for the prompt!