I don't know if this will be reassuring, but Tilly too was a dreadful biter when younger. Yelping and ignoring her seemed to excite her more (I think she was a bit of a bully!) but putting her out of the room for "timeout" seemed to calm her down. We also found forming fists with our hands, with the thumbs inside meant that she couldn't get a good grip on fingers, although knuckles got a gnawing! Although we did not see quick results from any of these techniques, I am pleased to say that at 10 months Tilly is a reformed character and has the gentlest of mouths. Like you, I didn't think she would ever get better, but she has and a firm "no biting!" works now when she gets a bit excited. She quickly turns her biting into a lick, as if to say sorry - it's very sweet really. So, I hope you will find, like me, that persistence and time will solve the problem.
Sympathies over the pjs. Tilly loved flapping trouser-legs and managed to rip my daughter's favourite trousers beyond repair - took a while for her to be forgiven for that one!
Sue