Hi. I can tell you that I am having the same problems with my pup He is now 5 months old and he was Biting etc. from 8 weeks old. It is mainly a teething problem...first teeth then cutting their second teeth etc. Mine finds my hands toes. etc. more exciting than his toys..but like me you must be firm with the pup. It will get better...I am saying a definate "No" each time he nips me etc. and put him down and ignore him for a short while.
Mine seems to be worse when he gets really excited when playing with toys..and sometimes turns his attention..and teeth on me..so I then stop playing and walk away.
I think if you look back at a lot of previous postings..you and I are not alone with this problem...so I hope it gets better for you too.
Lots of love and patience I think...its not easy ...I think I should have called my pup "nipper" . x
Chrisann