You could change to some M toe clips but you may find it awakward or your foot may slip out more. If you prefer to have more of your foot in the pedal (the ball of your foot or more) that definitely wont be the case with a smaller size. Clips, as mentioned, is another option as long as you are confortable with being "locked in." My buddy wears a 12.5 and he rode my bike a few times and got annoyed and just used the underside of the pedals.

I wear an 11 and I wish I had the large instead. I went from clips, which I had adjusted perfectly, to M clips and found I have less of my foot over the pedal. I have rediculous toe overlap on my frame (2"+ with 165 cranks and M toe clips) and I just rode a lot and got used to it. You'll be fine, just dont turn tight and start straight.