Hey littlebean, I got a lot of useful info from the Breast feeding support people. I felt the same like I couldn't tel what was happening so these are the highlights - forgive me if you know all this already:
So firstly there are three stages of them feeding, at first they glug away rapidly to get milk flowing, they then move on to tje second stage where they are doing a 'suck suck swallow' motion which you can visibly see when watching their chin. Finally they reach the last stage which is where they are getting the high calorie fatty milk you want them to be getting, you know they have reached this stage when they do a weird juddery movement, it almost feels like a vibration happens in their mouth or a fluttery feeling - so once they have got to that stage you know they have properly got to the good stuff. Then the support worker said that the baby should naturaly 'fall off the breast' when they are finished, so you shouldn't be taking them off to swap sides, you should wait for them to come off on their own and then wind them and offer the other side. Really they should be taking at least some of the second side each feed.
As my LO lost more than 10% of her birth weight in three days I was told to feed every 3 hours so I have to wake her up to feed her whether she is asking for it or not, this also makes it easier to feed as they don't get so panicky. Apparently the thrashing around and arching their backs etc is normal for a baby when it's really hungry.
Other things they said were that if it is hurting at all past the initial first couple of seconds of latching on then they are ok wrong and you should remove them and start again.
Also make sure you are totally relaxed and have everything to hand - a big drink of water, Lansinoh cream (soothes your nipples but also can help baby latch on if they are just sort of licking at you rather than sucking), Vaseline for your lips, muslin, pillow to prop yourself up etc. If you are comfortable it should work better.
One other thing is that if your baby appears to fall asleep while feeding then you should push their head further in towards your breast which should get them sucking again, if it doesn't then they said you should take your thumb and index finger and gently squeeze your Breast as you would to hand express with the idea being that you will squirt a bit of milk in their mouth and if they don't repsond to that by sucking again then they are done.
I was also told to try to express by hand or with a pump after every feed on both sides for 48 hours. It doesn't matter if nothing comes out, the point of it is to stimulate your breasts so they produce more milk because they think your baby needs it.
I think that's the main things to think about - hope it helps. I was a total state before the support lady came out to help because my milk wasn't properly in yet and I felt like I was starving my baby. Things have now got into the good routine though x