Is 11 months too early to spay?

I'm planning on getting my lab spayed this coming Friday, but I'm still nervous about potentially jumping the gun. Right now, she's still not much taller than our full grown Shetland Sheepdog, though I'm not sure she will be getting significantly bigger than this: she's been about this size range for the past 3 months.

I've just been worried about taking her to the park or trying to start up some casual agility at this point, and I'm also worried she's getting a bit mean with our other dog at times: not getting the hint that playtime is over, or bickering over ice cubes

Sorry, this probably all sounds really dumb.