As you probably know, neutering will not make her less of a handful.
There are two sides to consider here, her physical health and her social maturity.
Personally (having read the latest study out of UC Davis, which just confirmed and expanded on previous info) I'd be wary of spaying a medium/large breed bitch under about 2, though the health risks of spaying (and not spaying) vary by breed.
Some breeds are much more prone to mammary cancer than others, so earlier spaying is better for them. But the bitches of some breeds (esp larger ones) are more prone to spay incontinence than others, especially when spayed young, so they benefit from later spaying. There are also varying risks around other cancers and joint issues.
Social maturity in a larger dog won't hit until somewhere after the second birthday (I have an unspayed medium sized bitch who suddenly shifted, like a dial being turned, at about two and a half). They just get more sensible then: still happy to play, loads of energy etc but they become more attentive, less manic, and a little more assertive around other dogs (not aggressive, just clear about the rules).
You don't say if your bitch had had a season yet. Personally I'd put up with the hassle of a couple of seasons to see my bitch mature physically and mentally before stripping out an important set of hormones.
You have to do what works for you, but the UC Davis paper (Hart et al I think, published within the last year) is worth a scan.p
She sounds beautiful btw - that must be a lovely mix.