I nursed my 3 kids beyond a year, I had the same thing with all of them at various degrees. None of mine ever took bottles either. Sounds like you have tried to tell him, yet he cries then you can't nurse him at all. Anytime mine would bite, I would bring the baby's face right into my breast, and say NO! gently but firm your trying to teach them this isn't ok. It briefly cuts their air supply off. If it continued, I would stop nursing, set them on the floor and walk away. It shocks them the first time, and its brief so be prepared to do it again. My girlfriend would flick her sons ear and say no. I have used all the above depending which of my children you ask about. :) They will test you again, they look up at you while nursing and try again to see what you'll do, to watch your expression. Your going to have a crying baby regardless what you do. They always do sense your emotions, so if your nervous about nursing = biting he will know. So prepare yourself for the task, if possible have your spouse, mom, friend be there for support so you keep your patience. Walk outside so you don't hear the crying, come back in and sooth him, talk to him, humm, then try again.
As for let downs, Fenugreek worked great for me, I also took a Milk Thistle? When I called my vitamin store she knew just what to help me with. Did you consult with the Vitamin "Clerk"? There is also a Mothers Tea (grocery/vitamin store) to drink hot/cold to help with milk supply. You can increase your Fenugreek. Please, please check with them again. If they don't have the answer I will call my shop for you, its very late otherwise I would now.
As you mentioned, you need to increase your nursing to help increase your milk supply. You really have to increase your water intake. If you aren't doing this, this will quickly decrease your milk supply. Don't let anyone tell you your just drying up, its nonsense. If you are drinking the water, nursing rather than pumping (to increase supply) to stimualte your breast, you should be ok. Keep in mind, you need to rest/and get sleep. Nap while baby naps, its still ok to do, especially if you are trying to help supply.
Some other things I did, hot showers before nursing (not the easiest thing to do) warm compresses, or massage your breast before you nurse. Oh - and if your son is touching/ massaging your breast while nursing, or is twisting your other nipple, he is the one trying to get your milk to let down, let him. It would take less than a minute to let down. Those guys know what their doing.
If all else, call Le Lache League (LLL), they are in your phone book or online, and these gals know what they are talking about. They can guide you on a phone conversation how to help or attend a meeting, some may even meet with you right away. Warning, not all lactation ladies have nursed, and if they say they did, ask for how long. LLL, trains their leaders for a year of more before they quailify to advise. They are simplistic in thier teachings, and teach us as our grandmothers learned how to feed their children and those before us. I hope I have been of some help, please let me know of the outcome. I have enjoyed nursing my children and hope you are sucessful as well. It may be a long road for you, but one worth traveled.
My Best,
D.