bitting, nipping, tried everything help

I have a 3 month old female pit. Due to circumstances I had to take her at 7 weeks. She is in training cl$#@! and is so smart, she does all the commands the big dogs are supposed to do and shows them up. She also know to watche when it's feeding time and when she is doing wrong. The only thing I can't get is her to stop bitting my hands, and family memebers. 75 percent my hands, my dad doesn't get nipped much but even if I am holding her toy she will chew it and ever now and then go right for my hamds. If I pick her up or pet her when she's not just waking up she goes for my hands. I have tried ouch, yelp all off the startling so when that didn't work went to time outs. Always stay calm and $#@!ertive and soft spoken exspessially when crating her for time out. As of yesterday she started daycare for socialization and excersize since I live in Buffalo ny and have been snowed in with negative 30 temp. She's is doing amazing with everything I just want to stop this, is it teething? Is it because I train and disipline her? I spend the full day with her and working with her so her attention is on me. Please any info would help. Thanks

cameron and bella

bitting, nipping, tried everything help