J.G.
Sorry to hear that you are going through this. I know how stressful it can be. My almost 15 month old daughter never took to the bottle. Ever. I tried 3 or 4 different bottles and nipples before realizing she just wasn't going to do it. She would go 8-10 hours without drinking anything and I ended up having to come home during my lunch break to nurse her for about 5 months until she was able to start using the sippy cup. Your son may be old enough for you to try the sippy cup too. I would introduce it at each mealtime and let him play around with it so he can get used to it.
Before my daughter was able to use the sippy cup, my husband or the babysitter would feed her a little milk using a medicine dropper or baby spoon. It took forever, but they were able to get her to take about 2 ounces which is better than nothing.
Some of the things I tried to do with her that I had read/heard about were:
Feed her upright, in a bouncer, or with her back to someone's chest and make a game out of it by singing songs.
Feed her while standing or walking around
Try feeding her right when she wakes up or is dozing off and is really sleepy
Make sure the milk is really warm and run the nipple under hot water to warm it up
Good luck!
J.