How do I get all merge requests from Gitlab Api?

Currently I am trying to integrate Gitlab in my project and the problem I am facing is this. Documentation says that endpoint /api/v4/merge_request?scope=all should return all merge requests I can have access to. But what I am getting is only 20-21 MR(should be over 100). And I have access to 100 over MR. Any help would be helpful my method is below

public function getMerges() {
      $url = $this->url."/api/v4/merge_requests?scope=all";
      return $this->request($url, $this->auth);
 }