got / 've got / 've gotten in American English

Hi teachers

as far as I know,"gotten" is the past participle of the word "get" in American English. According to the following english usage pattern,past participle is used after "HAVE",

I 've finished all my assigments already.

Subject + HAVE + past participle

I do hear American say both"'ve got" and "'ve gotten" in their conversation,can u pls tell me the correct way to use them in AE?or are their meaning the same?

And,let say,if u r at a restaurant with 2 other friends,a waiter asks u how many people u have. which of the following is the correct one to reply?and why?

(1) We've got three.
(2) We got three.
(3) We've gotten three. (sounds a little odd to me)
(4) We have three.

Thank you!

[blacknomi]

Not (3).