Use OpenCV to detect small chessboard pattern

Question

I am currently working on a project where I need to indentify a chessboard pattern like this:

https://preview.ibb.co/g7Dnka/cow.jpg

I searched for some code that could do this and found the OpenCV function findChessboardCorners. I could test it successfully with some images. That's the code in C++:

#include <opencv2\core\core.hpp>
#include <opencv2\highgui\highgui.hpp>
#include <opencv2\imgproc\imgproc.hpp>
#include <opencv2\calib3d\calib3d.hpp>

#include <iostream>

using namespace cv;
using namespace std;

int main(int argc, char** argv)
{
    // read the file
    Mat image = imread("cow.jpg", IMREAD_COLOR);

    // check for valid image
    if (!image.data)
    {
        cout << "Could not open or find the image" << std::endl;
        return -1;
    }

    // grid size (cols, rows)
    Size size(7, 7);

    // store detected centers
    vector <Point2f> centers;

    bool sucess = findChessboardCorners(image, size, centers);

    cout << "find: " << sucess;

    // draw the chessboard
    drawChessboardCorners(image, size, Mat(centers), sucess);

    // display the result
    namedWindow("Display window", WINDOW_AUTOSIZE);
    imshow("Display window", image);

    waitKey(0);
    return 0;
}

My problem is that it only accepts chessboards with height and width bigger than 2 (counting only inner corners), but I'm working with 8 x 2 size.

Is there any way to bypass that or even writing my own function? Thanks for any help.