I want to finish it with the Mabel-method

The problem is, I stitched 43 stitches, and the lines are of a different length. I take another piece of Aida, 14 count, again a different length. I take a piece of 28 count linen, again a different length.
One is longer :

The other is longer, too:

And the linen is shorter a bit:

Now what do you suggest I do?

I had one idea, I put the white aida that was the less longer into a pot of fruit tea, to colour it and hopefully to shrink it just a tiny little bit - then it could be OK. Otherwise I don't know how to proceed. I am waiting for it to soak for a few hours now.
Another possibility: is it OK if I have less number of stitches but the same length? Then I will have to play with the whipstitch but perhaps it is doable...

Any ideas welcome