sazzermol, thanks for the extra info.
I would say the jury is still out.
Babies should definitely not lose weight after about day 4-5 - the further loss at day 10 should have provoked some action and it probably did, from what you say. The main action is ensuring frequent, effective feeding from both breasts at least, every time, and it's still not clear what's happening there....can you increase the no. of direct feeds?
Waiting for your breasts to refill is the opposite of what you need to do - this decreases supply. In the very short term, it may seem as if you have more milk (and in the short term, you do, at that moment) but in the medium and longer term, you make less.
Could be difficulty in getting a good, effective position, for some reason - but you say they have looked at that?
Can you increase the feeds and increase the number of 'sides' at each feed (switch nursing)?
It could be that all is well, but your description of him being fractious a lot of the time, and the slow weight gain, and the lack of poo, are not good signs.