If you think it could be that she wants something to occupy her hands you could try those nursing necklaces you can get? Or even an interesting (soft!) toy? Other than that, I think just keep attempting to prevent her doing it until she is old enough to "get it", or you might decide to wean if it gets too much. I don't think a 9mo would respond well to being swaddled. Maybe someone has another solution so this message will bump the thread for you.
Mine isn't a supply problem or I seriously doubt it is because it still literally pours out I've always had a really good supply and strong let down. Actually I hate the strong let down because its actually really uncomfortable every time! With my first baby I was regularly donating milk to a set of preemie twins and with this one for the first 4 months I was feeding her and pumping out enough to feed a second baby as my friend wanted to breastfeed but couldn't so asked me if I would consider expressing so her daughter could still have breastmilk. So whilst supply could be a problem in some cases it isn't for me. The biting, no matter how much I try to hold in a reaction I can't help it. I always yelp. It hurts I can't help it. The pinching I think she may be doing as a comfort thing...it sounds odd but she seems to understand it hurts and stop doing it for a bit but by the next feed she forgets and just does it again, almost like its subconscious or something. At least the biting isn't as often as the pinching. It's the pinching that's beginning to really kill me. I have bruises everywhere, earlier I managed to distract her with my ponytail for a little bit but not long unfortunately.
My ds does this all the time, my chest and neck look awful. I struggle with low supply issues and he tends to do this more when he can't get a let down or I don't have enough milk. Could this be a possibility?
Maybe just remove her and say "ouch, that hurts mummy, we touch nicely like this..." and demonstrate stroking her chest or arm or something? It was enough for me to just remove DS and end the feed, he'd get really upset and soon realised the connection, but maybe she's a bit young to realise yet?
If it's the reaction she finds funny, hard as it is you could try saying nothing and just removing her to teach her it's pointless to pinch etc as she won't get a reaction from you.
Some people with younger children find that when they bite, rather than instinctively pull them away, if you push the child into the breast so that they can't breathe easily, they will break the latch and come off themselves. I tried this but couldn't train myself into not pulling him off when it hurt so much. Could be worth a go for you, though, as while it won't hurt her, she might realise the link between her biting you and the unpleasant experience of it being difficult to breathe.
How old is she? My DS went through a phase like that at about 15 months or so. I found the best way to deal with it was to remove him from the breast and give him a time out every time he hurt me. Also explaining to her that she's hurting you might work if she's older, combined with the removal from breast. DS is now 2.3 and knows that if there is any funny business I will stop feeding him, so doesn't mess about. He hits and scratches at other random times though.
My daughter has bitten, pinched and scratched occasionally while nursing for a few months. To start with it was only occasionally, we would just stop nursing and then resume a short while later and she'd behave. The past couple of weeks she's done it more often and for two days we've had very few pleasant nursing sessions because she's pretty much just biting me and laughing about it. She's broken the skin on both sides now so its sore to feed at all. Wonderful! Also I have bruises across both boobs my chest and neck area and my arms where she's been pinching while feeding. I try to remove her hands and encourage her to do something else with them but the second I move her pinching hand she yanks off the breast and flaps both arms around screaming in protest. Also if I ever feed her in either loose clothing the she can get her hand into or topless she twists and pinches my other nipple. So obviously I try to keep that one covered so she can't. It's so strange because she's never had formula or a bottle or cup she's always flat out refused them. So why is she now causing so much trouble nursing?