I'm hoping Barb will pop in here, she will be able to give you some excellent suggestions, as she did for me when I was in a very similar boat to you!

I wouldn't be so concerned with whether they're 'good' feeds (although they need to be a reasonable length of time), rather, getting plenty of feeds into her. I would try to add another 2 feeds in, so she's having 8-9 in 24 hours. I think you'll find that will make the biggest difference. I agree that she needs to be comp fed for now to help get her weight up. All of this is best done under guidance, I would strongly recommend finding a good LC and getting them to help you through this. Unfortunately it's not as simple as it sounds, and you will need good support and advice. Definitely doable though! Once you start seeing at least one poo a day you can celebrate LOL.

Motilium might be something to think about if the extra feeds don't help. But I would be immediately giving her some extra feeds, and seeing how you go with that. I would suspect that within only a few days you will notice a difference in your baby.