I'm at my wits end

I have EBF my son the whole time. He's almost 6 months and I want to be done BF. But I can't get him to take a bottle. I've tried every bottle created, I've tried sippy cups, I've tried a straw sippy, I've tried a 360 cup. And nothing. He refuses. Am I just supposed to breastfeed forever? I need to go back to work. No, he won't take it for anyone else either. I'm at a loss and I'm starting to shed tears about this because I don't know what else to do. He'll drink maybe an ounce out of his 360 cup and then he starts throwing a fit until I nurse him. I just really don't know what else to do.