YogaMummy, it looks like you are figuring out the situation, but I will through in my 2p if it helps:
My DS pretty much lived on my breast for the first three weeks. During the day, I was sitting on the couch ALL DAY LONG for hours and hours. He was not too bad in the night, I could actually put him down in my bed, but we co-slept and I do remember feeding a lot in the night lying down (so this is slightly better than your situation). I also had an emergency c-section and because of it or all the drugs or whatever, my milk supply took forever to get to a decent level. DS lost a load of weight in the first week. In retrospect, my DS was feeding so much to build the supply up (the more demand, the more supply). Perhaps this is what your DD is doing. If it is the case, do no limit feeds (as your breastfeeding coordinator said). Just make yourself as comfy as possible on the couch, eat nice (microwavable ready-made) things, watch loads of films (subscribe to LoveFilm, it saved me!) and do not think about anything else. In the night, take DD into your bed, swaddle her (this may make it easier to put her down) and sleep with her latched onto your boob. And please believe me - it will not last. My DS got a lot better at 3 weeks. He is 11 weeks now, he still takes longer than average feeds, but we have a good life! He is snoring upstairs now in his own cot all by himself.
And I totally understand your emotions. I cursed my NCT classes a million times. I just wish they provided a more realistic picture of breastfeeding. I shed many tears and spent a lot of time feeling like an inadequate wreck and being afraid of being glued to the blasted couch FOREVER in those first three weeks. But it's ok. It's normal. And it will pass.
Perhaps try a wrap sling in the day. They are the coziest ones for a little baby.
I so feel fore you. It is sooooooo hard. But it will get better. Hang on there. You are doing fab.