hello
just wanted to offer some encouragement really. Sounds like you have managed very well with some really crapola advice from your HV! Or should that say, despite her advice.
From experience, BF-ing is one of the most demanding parts of new motherhood, but it does get easier. My DS also lost way over the expected 10% of his birthweight, but over a few weeks he started making it up. As long as you baby is producing half a dozen wet nappies, is active and alert (as a small baby can be), and is gaining some weight (nevermind the 6oz per week thing - some babies gain weight more slowly), then what's the problem?
You'll be feeling knackered, which is par for the course, so make sure you get to bed as early as poss (doesn't look like that's a goer at the moment, but your babe won't always be feeding so intensively), and take things as easy as you can. Forget housework, let it all stack up and accept any offers of help that you can. If you can afford to get your shopping on-line, do so. Eat well, drink plenty, and accept that for the next month or two you will need to park your ass on the sofa and have the baby attached to your boob for most of the day (and night!)
It does get easier, and in a couple of months you will actually find it all a breeze and relatively enjoyable.
Good luck.
PS Good website for any breastfeeding query is www.kellymom.com, also use the Association of Breastfeeding Mothers or LaLeche League for advice (they have websites).
PPS I had a very supportive partner and my mum helping out in the first month. When I got mastitis (several times), my mum would jump on the bus and come over with hot flannels to massage the lumps out (!) If you have a partner, close relative or a friend to give you practical and emotional support in these early days, lean on them heavily. It isn't as easy - initially - as it sounds in your antenatal breastfeeding "lesson" (where they show you how to hold a doll like a rugby ball and get you to memorise "nose to nipple".) But sounds like you are doing well so far