14month old bitch help

Hi, im currently experiencing problems withmy 14month old bitch who has become slightly aaggressive after I had her spayed in january. At first I thought it was a naughty phase but over the past month during walks shes started jumping up and biting my hand/arm or the top of the lead. When this occurs I stop and make her stand still and try and sort of calm her down but I cant determine what sets her off and im really unsure on what to do, if anyone could help me id appreciate it

Daisy used to do this too but not aggressively. I would make her sit and stay like a time out, then start walking again and if she did it again stop and repeat until she walked properly again. This link may also help   

http://staffy-bull-terrier.com/stop_your_staffy_puppy_biting

Welcome to the forum, come and say hi when you get a minute   

staffy-bull-terrier.niceboard.com/f7-new-member-introductions

May I ask why she was spayed in January at that young age, was it for medical reasons ?

Thanks ill read the guide, and she'd had her first season and vet said it would be fine so I did it?

At first I thought it was a naughty phase but over the past month during walks shes started jumping up and biting my hand/arm or the top of the lead.

That's not aggression it's playing. Axl used to do it when he got over excited, say I ran with him on lead he'd jump up and bite the lead. A little bit of training and she'll settle down

Hello! Agree with others that this is likely play rather than aggression.. Is she growling/freezing up/staring before jumping up and grabbing? After her spay, did she have a period of being kept indoors due to recovery?

Has she never done anything like this before? She's doesn't become over stimulated by any sights/sounds/smells etc?