Hi peanutter,
Your baby is of a certain age. It's an age when they start to get very interested in the world around them and distracted at feed times. The behaviour you describe is quite typical of this phase, unfortunately.
It may well be that he is getting what he needs in those few short minutes when he feeds well. If he wants to get off, let him go.
My DS went from looooong feeds to very short ones almost over night at this age. It stressed me out and I kept trying to force him to feed. He then started to refuse the breast.
I found that feeding him in a quiet darkened room helped a bit. But the biggest thing that helped was relaxing and just letting him set the pace.

Your milk is fine - trust your breasts to get it right. Your baby also knows what he needs - he's being a bit difficult at the moment, but he won't actually starve himself. Keep an eye on his nappies if you're at all worried about his intake. (has he started waking for mroe feeds at night by any chance, that's quite common at this age also - joy!)

Remember you can always call the ABA for advice & support too - they will actually try to help you rather than just telling you to grab some formula 1800-686-2-686