Spring Two Steps Forward, One Step Back

And what of those Spring Forward socks? Well, according to the above photo, they appear to be motoring along nicely. Indeed, I’ve started on the second one.
But wait a minute – started on the second one before finishing the first?
Yes.
Of course, plenty of people do this – they knit their pairs of socks simultaneously, on a circular needle using the magic loop technique. But that’s not what’s going on here.
My friends, all is not rosy in the garden.
It was going so well! I’d turned the heel (with its delicious heel flap), and was haring along towards the toe, when I decided I’d like to try the sock on, just to see how it looked.
Blasted thing wouldn’t go over my heel! Sockblocked!!!
Now, the Spring Forward pattern says that the foot will stretch to 11 inches, and the leg to 12 inches. The circumference of my foot at the widest point (under heel, over front of ankle) is just short of 12 inches, so I’d thought it would be OK – after all, it’s the leg part that needs to get past that wide point.
Unwarranted assumption, alas. The leg part went on fine, but I got stuck at the heel turn. It almost worked – and oh, how I tried to make it work! – but in the end I had to concede the feet (sorry).
So what next? Clearly, the natural thing to do would be to stuff the project into a drawer and never speak of it again. Apparently I am an unnatural knitter, because instead, I did maths.
My sock will stretch to 11 inches at the heel turn, I said.
It needs to stretch to 12 inches.
One inch (the shortfall) is about 9% of 11.
I am working on 2.25mm needles.
9% of 2.25mm is 0.2mm.
2.25 + 0.2 is 2.45.
Therefore, if I use 2.5mm needles, that should give me the increase I need.
So that’s what I’m doing. The second sock up there is being knitted on 2.5mm needles, and if that works (I’ll check it once the heel is turned), I’ll frog the first one and reknit it.
Perhaps they’ll be done by spring.

What a cunning plan!
Ooh, cunning. I’d love homemade socks but I’d need to buy all new shoes, to accommodate the extra width. My shoes barely fit my feet widthwise; warm socks are out of the question.
*preens*
It seems to have worked, moreover. I’m about halfway up the foot of the new sock.