M.,
I have been in that boat with you! My 8 1/2 m.o. son went through the same thing a couple of weeks ago. I say, if you want to nurse him until he is a year, then go for it! It may be a tough week or so, but it is best for him.
He may not be eating as well because he doesn't feel good. If he is congested then his tummy may be full of snot (I know, gross!) Imagine how you feel about eating when you are under the weather...especially if when you add a toothache on top of it! He will feel better soon and get back to his normal routine. Hang in there and don't give up on him.
Don't worry so much about you milk supply slowing down. You will not dry up due to a week of poor feedings. Once he is feeling better, he will eat more, which will trigger your body to make more milk. Also, try eating more oatmeal (for breakfast, cookies...) it is a natural milk-making enhancer:)I agree with the other advice about pumping more, drinking more water, and NOT supplementing with formula (unless you absolutely HAVE to, although I have never done this). If you cannot tolerate nursing due to your nipples hurting but can tolerate pumping...then keep at it.
As for the biting, my son does that too. He tends to bite when he is teething and when I attempt to nurse him but he isn't hungry. I have gently flicked him on the cheek and firmly said "no bite, that hurts". I then offer a breast again and if he bites, I take it away. I won't attempt to nurse him unless he gives me signals that he wants to nurse. If he is hungry, he will nurse and not bite. If he is not hungry, why force him to nurse???
You seem to be doing a great job by putting your son's best interests first. He is haveing a rough week so be patient with him. Everyone has to do what is right for them and their kids, but like I said before, if you want to nurse for 1 year, then do it! Just please, don't quite nursing him because it is the "easy" way out. I don't want to harp too much, but breastmilk really is the best thing for him !-)