I need some help understanding this..
Yesterday we were in the garden,Oka and I, playing. She was chasing the ball down the garden, i would call her she would bound back (with the ball), i would take her collar whilst offering a treat (recall as taught by our puppy class), then throing the ball again.. we were having fun. Then on one return she grabbed my sleeve (by mistake i think) and i said 'off', she then turned her mouth to grab my arm. I said 'no, off' and she let go and i stood up to throw the ball again. she then started to jump up at me and bite my clothes. i crossed my arms and turned away she barked at me and bit my trousers and shoes. I thought i'll end this here and walked inside in the thought of shutting her out for a minute for a time out.... She bit at the back of my leg and has scored a 3inch scrape across it which today has some little bruising around. i yelled "ow" when she bit me as it really hurt.

After her time out i went back out and she greeted me with her ears flat back and sat down pawing at me (her normal greeting). We played with the ball but no recall stuff and then she did the same...caught my sleeve when i stroked her and i said "off" and she started jumping again etc...didn't bite my leg though.
Today she has done similar but not as bad;jumped up at me when i sat down (after being out playing with her), i tell her 'off', barking and glaring at me then tries to bite me when i ignore her. . I put her in time out for a minute or two. She tends to whine when i put her in it, not sure if she realises she has done wrong or if she thinks i'll let her out quicker?!
She sometimes she has snapped her jaws at me if i tell her off.
She'd stopped 99% of her mouthing and is great with lots of things - i can look in her ears, eyes, mouth, play with her feet with nothing so much as a head turn. I can't workout why she did this. I'm not sure if she was tired, if she's teething or just trying to "answer back".
Anyway sorry for the essay, i was quite shocked at her behaviour. If someone can tell me if what i am doing is right or any other suggestions i would be gratefull. She is 16 weeks - that ticker is wrong