How to plot several .jpg images in one figure

Hello: I want to place several images I have in one figure so that I end up with seven images (at different sizes) on one same page. The images are positiones in a 6x2 cell array that I have created using subplot. The position of each individual image would be as follows: image1:cells 1,2,7,8 image2: cell 3 image3: cell 4 image4: cell 9 image5: cell 10 image6: cells 5,6 image7: cells 11,12 So in the end I end up with different sizes of images. The problem is the following. Whenever I run my code the images are not adjacent to one another. They are separated by blanck spaces, and image 1 seems to be the same size as image 6 and 7 although it should be double it's size. My code is:

    [X1,map1]=imread('IMG_4866.jpg');%carga imagen a
    [X2,map2]=imread('IMG_4867.jpg');%carga imagen b
    [X3,map3]=imread('IMG_4868.jpg');%carga imagen c
    [X4,map4]=imread('IMG_4869.jpg');%carga imagen d
    [X5,map5]=imread('IMG_4915.jpg');%carga imagen e
    [X6,map6]=imread('IMG_4916.jpg');%carga imagen f
    [X7,map7]=imread('IMG_3922.jpg');%carga imagen f2 
    subplot(2,6,[1,2,7,8]), imshow(X1,map1)
    subplot(2,6,3), imshow(X2,map2)
    subplot(2,6,4), imshow(X3,map3)
    subplot(2,6,9), imshow(X4,map5)
    subplot(2,6,10), imshow(X5,map5)
    subplot(2,6,[5 6]), imshow(X6,map6)
  subplot(2,6,[11 12]), imshow(X7,map7)

Please I need some help so that I can get the images adjacent to one another as if it were three columns, and the first column had one row, second column 4 and third column 2. Thanks to everyone in advance